MainframeMaster

COBOL Tutorial

COBOL EXTERNAL Clause

The EXTERNAL clause represents a sophisticated data sharing mechanism in COBOL programming, enabling seamless communication and data exchange between multiple programs within the same run unit. This clause facilitates the creation of external data items that transcend individual program boundaries, supporting complex application architectures that require shared state management, inter-program communication, and coordinated data processing across multiple program modules while maintaining data integrity and consistency throughout the execution environment.

Main Program with EXTERNAL Data

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IDENTIFICATION DIVISION.
PROGRAM-ID. MAIN-EXTERNAL-PROGRAM.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
*> External data items shared across programs
01  EXTERNAL-SYSTEM-CONTROL    EXTERNAL.
    05  SYSTEM-STATUS           PIC X(10) VALUE 'STARTING'.
        88  SYSTEM-ACTIVE       VALUE 'ACTIVE'.
        88  SYSTEM-INACTIVE     VALUE 'INACTIVE'.
        88  SYSTEM-ERROR        VALUE 'ERROR'.
        88  SYSTEM-SHUTDOWN     VALUE 'SHUTDOWN'.
    05  CURRENT-USER-ID         PIC X(8) VALUE 'ADMIN001'.
    05  SESSION-ID              PIC X(20) VALUE SPACES.
    05  PROCESSING-MODE         PIC X(10) VALUE 'BATCH'.
        88  BATCH-MODE          VALUE 'BATCH'.
        88  INTERACTIVE-MODE    VALUE 'INTERACT'.
        88  BACKGROUND-MODE     VALUE 'BACKGROUND'.
    05  SYSTEM-DATE-TIME        PIC X(14) VALUE SPACES.
    05  TRANSACTION-COUNTER     PIC 9(10) VALUE 0.
    05  ERROR-COUNTER           PIC 9(5) VALUE 0.
    05  SUCCESS-COUNTER         PIC 9(8) VALUE 0.
 
01  EXTERNAL-BUSINESS-DATA     EXTERNAL.
    05  CURRENT-CUSTOMER.
        10  CUSTOMER-ID         PIC 9(8) VALUE 0.
        10  CUSTOMER-NAME       PIC X(30) VALUE SPACES.
        10  CUSTOMER-TYPE       PIC X(10) VALUE SPACES.
            88  PREMIUM-CUSTOMER VALUE 'PREMIUM'.
            88  STANDARD-CUSTOMER VALUE 'STANDARD'.
            88  VIP-CUSTOMER    VALUE 'VIP'.
        10  ACCOUNT-BALANCE     PIC 9(9)V99 VALUE 0.
        10  CREDIT-LIMIT        PIC 9(9)V99 VALUE 0.
        10  LAST-ACTIVITY-DATE  PIC 9(8) VALUE 0.
    05  CURRENT-TRANSACTION.
        10  TRANSACTION-ID      PIC 9(10) VALUE 0.
        10  TRANSACTION-TYPE    PIC X(10) VALUE SPACES.
            88  DEPOSIT-TRANS   VALUE 'DEPOSIT'.
            88  WITHDRAWAL-TRANS VALUE 'WITHDRAWAL'.
            88  TRANSFER-TRANS  VALUE 'TRANSFER'.
            88  PAYMENT-TRANS   VALUE 'PAYMENT'.
        10  TRANSACTION-AMOUNT  PIC 9(9)V99 VALUE 0.
        10  TRANSACTION-DATE    PIC 9(8) VALUE 0.
        10  TRANSACTION-TIME    PIC 9(6) VALUE 0.
        10  TRANSACTION-STATUS  PIC X(10) VALUE SPACES.
            88  TRANS-PENDING   VALUE 'PENDING'.
            88  TRANS-COMPLETED VALUE 'COMPLETED'.
            88  TRANS-FAILED    VALUE 'FAILED'.
            88  TRANS-CANCELLED VALUE 'CANCELLED'.
 
01  EXTERNAL-CONFIGURATION     EXTERNAL.
    05  APPLICATION-SETTINGS.
        10  MAX-RETRY-COUNT     PIC 9(2) VALUE 3.
        10  TIMEOUT-SECONDS     PIC 9(4) VALUE 30.
        10  LOG-LEVEL           PIC 9 VALUE 2.
            88  LOG-ERROR-ONLY  VALUE 1.
            88  LOG-NORMAL      VALUE 2.
            88  LOG-VERBOSE     VALUE 3.
            88  LOG-DEBUG       VALUE 4.
        10  BACKUP-ENABLED      PIC X VALUE 'Y'.
            88  BACKUP-ON       VALUE 'Y'.
            88  BACKUP-OFF      VALUE 'N'.
        10  ENCRYPTION-ENABLED  PIC X VALUE 'Y'.
            88  ENCRYPTION-ON   VALUE 'Y'.
            88  ENCRYPTION-OFF  VALUE 'N'.
    05  DATABASE-SETTINGS.
        10  DB-CONNECTION-STRING PIC X(100) VALUE SPACES.
        10  DB-TIMEOUT          PIC 9(4) VALUE 60.
        10  DB-POOL-SIZE        PIC 9(3) VALUE 10.
        10  DB-RETRY-COUNT      PIC 9(2) VALUE 5.
    05  SECURITY-SETTINGS.
        10  PASSWORD-COMPLEXITY PIC 9 VALUE 3.
        10  SESSION-TIMEOUT     PIC 9(4) VALUE 1800.
        10  AUDIT-ENABLED       PIC X VALUE 'Y'.
            88  AUDIT-ON        VALUE 'Y'.
            88  AUDIT-OFF       VALUE 'N'.
        10  ENCRYPTION-LEVEL    PIC 9 VALUE 2.
 
01  EXTERNAL-STATISTICS        EXTERNAL.
    05  PERFORMANCE-METRICS.
        10  TOTAL-TRANSACTIONS  PIC 9(10) VALUE 0.
        10  SUCCESSFUL-TRANS    PIC 9(10) VALUE 0.
        10  FAILED-TRANS        PIC 9(8) VALUE 0.
        10  AVERAGE-RESPONSE-TIME PIC 9(6)V99 VALUE 0.
        10  PEAK-RESPONSE-TIME  PIC 9(6)V99 VALUE 0.
        10  MINIMUM-RESPONSE-TIME PIC 9(6)V99 VALUE 999999.99.
    05  SYSTEM-METRICS.
        10  PROGRAMS-CALLED     PIC 9(6) VALUE 0.
        10  MEMORY-USAGE        PIC 9(8) VALUE 0.
        10  CPU-TIME-USED       PIC 9(8)V99 VALUE 0.
        10  IO-OPERATIONS       PIC 9(9) VALUE 0.
        10  NETWORK-CALLS       PIC 9(7) VALUE 0.
    05  BUSINESS-METRICS.
        10  CUSTOMERS-PROCESSED PIC 9(8) VALUE 0.
        10  ACCOUNTS-UPDATED    PIC 9(8) VALUE 0.
        10  REPORTS-GENERATED   PIC 9(6) VALUE 0.
        10  ALERTS-SENT         PIC 9(5) VALUE 0.
        10  BACKUPS-COMPLETED   PIC 9(4) VALUE 0.
 
*> Local working storage for main program
01  LOCAL-CONTROL-VARIABLES.
    05  PROGRAM-NAME            PIC X(8) VALUE 'MAINPGM'.
    05  SUBPROGRAM-NAME         PIC X(8) VALUE SPACES.
    05  OPERATION-STATUS        PIC X(10) VALUE SPACES.
    05  LOOP-COUNTER            PIC 9(4) VALUE 0.
    05  CALL-COUNTER            PIC 9(5) VALUE 0.
 
PROCEDURE DIVISION.
MAIN-PROCESSING.
    PERFORM INITIALIZE-EXTERNAL-DATA
    PERFORM DEMONSTRATE-EXTERNAL-SHARING
    PERFORM CALL-SUBPROGRAMS-WITH-EXTERNAL
    PERFORM DISPLAY-EXTERNAL-STATISTICS
    PERFORM CLEANUP-EXTERNAL-DATA
    STOP RUN.
 
INITIALIZE-EXTERNAL-DATA.
    DISPLAY 'Initializing external data in main program...'
    
    *> Initialize system control
    SET SYSTEM-ACTIVE TO TRUE
    MOVE 'ADMIN001' TO CURRENT-USER-ID
    MOVE FUNCTION CURRENT-DATE TO SYSTEM-DATE-TIME
    MOVE FUNCTION CURRENT-DATE TO SESSION-ID
    SET BATCH-MODE TO TRUE
    
    *> Initialize business data
    MOVE 12345678 TO CUSTOMER-ID
    MOVE 'ACME CORPORATION' TO CUSTOMER-NAME
    SET PREMIUM-CUSTOMER TO TRUE
    MOVE 150000.75 TO ACCOUNT-BALANCE
    MOVE 200000.00 TO CREDIT-LIMIT
    MOVE 20240115 TO LAST-ACTIVITY-DATE
    
    *> Initialize transaction
    MOVE 2024000001 TO TRANSACTION-ID
    SET DEPOSIT-TRANS TO TRUE
    MOVE 5000.00 TO TRANSACTION-AMOUNT
    MOVE 20240115 TO TRANSACTION-DATE
    MOVE 143000 TO TRANSACTION-TIME
    SET TRANS-PENDING TO TRUE
    
    *> Initialize configuration
    MOVE 5 TO MAX-RETRY-COUNT
    MOVE 45 TO TIMEOUT-SECONDS
    SET LOG-NORMAL TO TRUE
    SET BACKUP-ON TO TRUE
    SET ENCRYPTION-ON TO TRUE
    
    MOVE 'SERVER=MAINFRAME;DB=COBOL;USER=ADMIN' TO DB-CONNECTION-STRING
    MOVE 120 TO DB-TIMEOUT
    MOVE 20 TO DB-POOL-SIZE
    MOVE 3 TO DB-RETRY-COUNT
    
    MOVE 4 TO PASSWORD-COMPLEXITY
    MOVE 3600 TO SESSION-TIMEOUT
    SET AUDIT-ON TO TRUE
    MOVE 3 TO ENCRYPTION-LEVEL
    
    DISPLAY 'External data initialization completed'
    DISPLAY 'System Status: ' SYSTEM-STATUS
    DISPLAY 'Current User: ' CURRENT-USER-ID
    DISPLAY 'Session ID: ' SESSION-ID
    DISPLAY 'Customer: ' CUSTOMER-ID ' - ' CUSTOMER-NAME.
 
DEMONSTRATE-EXTERNAL-SHARING.
    DISPLAY 'Demonstrating external data sharing...'
    
    *> Modify external data that will be visible to subprograms
    ADD 1 TO TRANSACTION-COUNTER
    ADD 1 TO SUCCESS-COUNTER
    
    DISPLAY 'Transaction Counter: ' TRANSACTION-COUNTER
    DISPLAY 'Success Counter: ' SUCCESS-COUNTER
    
    *> Update business data
    ADD 1000.00 TO ACCOUNT-BALANCE
    SET TRANS-COMPLETED TO TRUE
    
    DISPLAY 'Updated Account Balance: ' ACCOUNT-BALANCE
    DISPLAY 'Transaction Status: ' TRANSACTION-STATUS
    
    *> Update statistics
    ADD 1 TO TOTAL-TRANSACTIONS
    ADD 1 TO SUCCESSFUL-TRANS
    ADD 1 TO CUSTOMERS-PROCESSED
    
    DISPLAY 'Total Transactions: ' TOTAL-TRANSACTIONS
    DISPLAY 'Successful Transactions: ' SUCCESSFUL-TRANS.
 
CALL-SUBPROGRAMS-WITH-EXTERNAL.
    DISPLAY 'Calling subprograms that access external data...'
    
    *> Call customer processing subprogram
    MOVE 'CUSTPROC' TO SUBPROGRAM-NAME
    CALL SUBPROGRAM-NAME
    ADD 1 TO CALL-COUNTER
    
    *> Call transaction processing subprogram
    MOVE 'TRANPROC' TO SUBPROGRAM-NAME
    CALL SUBPROGRAM-NAME
    ADD 1 TO CALL-COUNTER
    
    *> Call reporting subprogram
    MOVE 'REPTPROC' TO SUBPROGRAM-NAME
    CALL SUBPROGRAM-NAME
    ADD 1 TO CALL-COUNTER
    
    *> Call audit subprogram
    MOVE 'AUDTPROC' TO SUBPROGRAM-NAME
    CALL SUBPROGRAM-NAME
    ADD 1 TO CALL-COUNTER
    
    DISPLAY 'Subprograms called: ' CALL-COUNTER
    DISPLAY 'Programs called (external): ' PROGRAMS-CALLED.
 
DISPLAY-EXTERNAL-STATISTICS.
    DISPLAY 'External Data Statistics:'
    DISPLAY '========================'
    DISPLAY 'System Status: ' SYSTEM-STATUS
    DISPLAY 'Current User: ' CURRENT-USER-ID
    DISPLAY 'Processing Mode: ' PROCESSING-MODE
    DISPLAY 'Transaction Counter: ' TRANSACTION-COUNTER
    DISPLAY 'Error Counter: ' ERROR-COUNTER
    DISPLAY 'Success Counter: ' SUCCESS-COUNTER
    DISPLAY ''
    DISPLAY 'Customer Information:'
    DISPLAY 'Customer ID: ' CUSTOMER-ID
    DISPLAY 'Customer Name: ' CUSTOMER-NAME
    DISPLAY 'Customer Type: ' CUSTOMER-TYPE
    DISPLAY 'Account Balance: ' ACCOUNT-BALANCE
    DISPLAY 'Credit Limit: ' CREDIT-LIMIT
    DISPLAY ''
    DISPLAY 'Transaction Information:'
    DISPLAY 'Transaction ID: ' TRANSACTION-ID
    DISPLAY 'Transaction Type: ' TRANSACTION-TYPE
    DISPLAY 'Transaction Amount: ' TRANSACTION-AMOUNT
    DISPLAY 'Transaction Status: ' TRANSACTION-STATUS
    DISPLAY ''
    DISPLAY 'Performance Metrics:'
    DISPLAY 'Total Transactions: ' TOTAL-TRANSACTIONS
    DISPLAY 'Successful Transactions: ' SUCCESSFUL-TRANS
    DISPLAY 'Failed Transactions: ' FAILED-TRANS
    DISPLAY 'Programs Called: ' PROGRAMS-CALLED
    DISPLAY 'Customers Processed: ' CUSTOMERS-PROCESSED
    DISPLAY 'Accounts Updated: ' ACCOUNTS-UPDATED.
 
CLEANUP-EXTERNAL-DATA.
    DISPLAY 'Cleaning up external data...'
    
    SET SYSTEM-SHUTDOWN TO TRUE
    MOVE 'CLEANUP' TO PROCESSING-MODE
    
    DISPLAY 'System Status: ' SYSTEM-STATUS
    DISPLAY 'Processing Mode: ' PROCESSING-MODE
    DISPLAY 'External data cleanup completed'.

Customer Processing Subprogram

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IDENTIFICATION DIVISION.
PROGRAM-ID. CUSTPROC.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
*> External data items - must match main program declarations
01  EXTERNAL-SYSTEM-CONTROL    EXTERNAL.
    05  SYSTEM-STATUS           PIC X(10).
        88  SYSTEM-ACTIVE       VALUE 'ACTIVE'.
        88  SYSTEM-INACTIVE     VALUE 'INACTIVE'.
        88  SYSTEM-ERROR        VALUE 'ERROR'.
        88  SYSTEM-SHUTDOWN     VALUE 'SHUTDOWN'.
    05  CURRENT-USER-ID         PIC X(8).
    05  SESSION-ID              PIC X(20).
    05  PROCESSING-MODE         PIC X(10).
        88  BATCH-MODE          VALUE 'BATCH'.
        88  INTERACTIVE-MODE    VALUE 'INTERACT'.
        88  BACKGROUND-MODE     VALUE 'BACKGROUND'.
    05  SYSTEM-DATE-TIME        PIC X(14).
    05  TRANSACTION-COUNTER     PIC 9(10).
    05  ERROR-COUNTER           PIC 9(5).
    05  SUCCESS-COUNTER         PIC 9(8).
 
01  EXTERNAL-BUSINESS-DATA     EXTERNAL.
    05  CURRENT-CUSTOMER.
        10  CUSTOMER-ID         PIC 9(8).
        10  CUSTOMER-NAME       PIC X(30).
        10  CUSTOMER-TYPE       PIC X(10).
            88  PREMIUM-CUSTOMER VALUE 'PREMIUM'.
            88  STANDARD-CUSTOMER VALUE 'STANDARD'.
            88  VIP-CUSTOMER    VALUE 'VIP'.
        10  ACCOUNT-BALANCE     PIC 9(9)V99.
        10  CREDIT-LIMIT        PIC 9(9)V99.
        10  LAST-ACTIVITY-DATE  PIC 9(8).
    05  CURRENT-TRANSACTION.
        10  TRANSACTION-ID      PIC 9(10).
        10  TRANSACTION-TYPE    PIC X(10).
            88  DEPOSIT-TRANS   VALUE 'DEPOSIT'.
            88  WITHDRAWAL-TRANS VALUE 'WITHDRAWAL'.
            88  TRANSFER-TRANS  VALUE 'TRANSFER'.
            88  PAYMENT-TRANS   VALUE 'PAYMENT'.
        10  TRANSACTION-AMOUNT  PIC 9(9)V99.
        10  TRANSACTION-DATE    PIC 9(8).
        10  TRANSACTION-TIME    PIC 9(6).
        10  TRANSACTION-STATUS  PIC X(10).
            88  TRANS-PENDING   VALUE 'PENDING'.
            88  TRANS-COMPLETED VALUE 'COMPLETED'.
            88  TRANS-FAILED    VALUE 'FAILED'.
            88  TRANS-CANCELLED VALUE 'CANCELLED'.
 
01  EXTERNAL-STATISTICS        EXTERNAL.
    05  PERFORMANCE-METRICS.
        10  TOTAL-TRANSACTIONS  PIC 9(10).
        10  SUCCESSFUL-TRANS    PIC 9(10).
        10  FAILED-TRANS        PIC 9(8).
        10  AVERAGE-RESPONSE-TIME PIC 9(6)V99.
        10  PEAK-RESPONSE-TIME  PIC 9(6)V99.
        10  MINIMUM-RESPONSE-TIME PIC 9(6)V99.
    05  SYSTEM-METRICS.
        10  PROGRAMS-CALLED     PIC 9(6).
        10  MEMORY-USAGE        PIC 9(8).
        10  CPU-TIME-USED       PIC 9(8)V99.
        10  IO-OPERATIONS       PIC 9(9).
        10  NETWORK-CALLS       PIC 9(7).
    05  BUSINESS-METRICS.
        10  CUSTOMERS-PROCESSED PIC 9(8).
        10  ACCOUNTS-UPDATED    PIC 9(8).
        10  REPORTS-GENERATED   PIC 9(6).
        10  ALERTS-SENT         PIC 9(5).
        10  BACKUPS-COMPLETED   PIC 9(4).
 
*> Local working storage for customer processing
01  LOCAL-CUSTOMER-VARIABLES.
    05  PROCESSING-RESULT       PIC X(10) VALUE SPACES.
    05  VALIDATION-STATUS       PIC X VALUE 'P'.
        88  VALIDATION-PASSED   VALUE 'P'.
        88  VALIDATION-FAILED   VALUE 'F'.
    05  CUSTOMER-CATEGORY       PIC X(15) VALUE SPACES.
    05  PROCESSING-TIME         PIC 9(6)V99 VALUE 0.
    05  CUSTOMER-SCORE          PIC 9(3) VALUE 0.
 
PROCEDURE DIVISION.
CUSTOMER-PROCESSING.
    DISPLAY 'Customer Processing Subprogram Started'
    DISPLAY 'Accessing external data...'
    
    PERFORM VALIDATE-CUSTOMER-DATA
    PERFORM PROCESS-CUSTOMER-ACCOUNT
    PERFORM UPDATE-CUSTOMER-STATISTICS
    PERFORM DISPLAY-CUSTOMER-RESULTS
    
    DISPLAY 'Customer Processing Subprogram Completed'
    EXIT PROGRAM.
 
VALIDATE-CUSTOMER-DATA.
    DISPLAY 'Validating customer data from external storage...'
    
    *> Access external customer data
    DISPLAY 'Customer ID: ' CUSTOMER-ID
    DISPLAY 'Customer Name: ' CUSTOMER-NAME
    DISPLAY 'Customer Type: ' CUSTOMER-TYPE
    DISPLAY 'Account Balance: ' ACCOUNT-BALANCE
    
    *> Validate customer data
    IF CUSTOMER-ID > 0 AND CUSTOMER-ID < 99999999
        IF CUSTOMER-NAME NOT = SPACES
            IF ACCOUNT-BALANCE >= 0
                SET VALIDATION-PASSED TO TRUE
                MOVE 'VALID' TO PROCESSING-RESULT
                DISPLAY 'Customer data validation passed'
            ELSE
                SET VALIDATION-FAILED TO TRUE
                MOVE 'INVALID' TO PROCESSING-RESULT
                DISPLAY 'Invalid account balance'
                ADD 1 TO ERROR-COUNTER
            END-IF
        ELSE
            SET VALIDATION-FAILED TO TRUE
            MOVE 'INVALID' TO PROCESSING-RESULT
            DISPLAY 'Invalid customer name'
            ADD 1 TO ERROR-COUNTER
        END-IF
    ELSE
        SET VALIDATION-FAILED TO TRUE
        MOVE 'INVALID' TO PROCESSING-RESULT
        DISPLAY 'Invalid customer ID'
        ADD 1 TO ERROR-COUNTER
    END-IF.
 
PROCESS-CUSTOMER-ACCOUNT.
    DISPLAY 'Processing customer account...'
    
    IF VALIDATION-PASSED
        *> Determine customer category
        IF PREMIUM-CUSTOMER
            MOVE 'PREMIUM' TO CUSTOMER-CATEGORY
            MOVE 95 TO CUSTOMER-SCORE
        ELSE
            IF STANDARD-CUSTOMER
                MOVE 'STANDARD' TO CUSTOMER-CATEGORY
                MOVE 75 TO CUSTOMER-SCORE
            ELSE
                IF VIP-CUSTOMER
                    MOVE 'VIP' TO CUSTOMER-CATEGORY
                    MOVE 99 TO CUSTOMER-SCORE
                ELSE
                    MOVE 'UNKNOWN' TO CUSTOMER-CATEGORY
                    MOVE 50 TO CUSTOMER-SCORE
                END-IF
            END-IF
        END-IF
        
        *> Update account balance based on customer type
        IF PREMIUM-CUSTOMER
            COMPUTE ACCOUNT-BALANCE = ACCOUNT-BALANCE * 1.001
            DISPLAY 'Premium customer bonus applied'
        END-IF
        
        *> Update last activity date
        MOVE FUNCTION CURRENT-DATE(1:8) TO LAST-ACTIVITY-DATE
        
        DISPLAY 'Customer Category: ' CUSTOMER-CATEGORY
        DISPLAY 'Customer Score: ' CUSTOMER-SCORE
        DISPLAY 'Updated Balance: ' ACCOUNT-BALANCE
        DISPLAY 'Last Activity: ' LAST-ACTIVITY-DATE
        
        ADD 1 TO SUCCESS-COUNTER
        ADD 1 TO ACCOUNTS-UPDATED
    ELSE
        DISPLAY 'Customer processing skipped due to validation failure'
        ADD 1 TO FAILED-TRANS
    END-IF.
 
UPDATE-CUSTOMER-STATISTICS.
    DISPLAY 'Updating customer statistics...'
    
    *> Update external statistics
    ADD 1 TO PROGRAMS-CALLED
    ADD 1 TO CUSTOMERS-PROCESSED
    
    *> Calculate processing time (simulated)
    MOVE 125.50 TO PROCESSING-TIME
    
    *> Update response time metrics
    IF PROCESSING-TIME > PEAK-RESPONSE-TIME
        MOVE PROCESSING-TIME TO PEAK-RESPONSE-TIME
    END-IF
    
    IF PROCESSING-TIME < MINIMUM-RESPONSE-TIME
        MOVE PROCESSING-TIME TO MINIMUM-RESPONSE-TIME
    END-IF
    
    *> Update average response time
    COMPUTE AVERAGE-RESPONSE-TIME = 
        (AVERAGE-RESPONSE-TIME + PROCESSING-TIME) / 2
    
    DISPLAY 'Processing Time: ' PROCESSING-TIME ' ms'
    DISPLAY 'Peak Response Time: ' PEAK-RESPONSE-TIME ' ms'
    DISPLAY 'Average Response Time: ' AVERAGE-RESPONSE-TIME ' ms'.
 
DISPLAY-CUSTOMER-RESULTS.
    DISPLAY 'Customer Processing Results:'
    DISPLAY '==========================='
    DISPLAY 'Processing Result: ' PROCESSING-RESULT
    DISPLAY 'Validation Status: ' VALIDATION-STATUS
    DISPLAY 'Customer Category: ' CUSTOMER-CATEGORY
    DISPLAY 'Customer Score: ' CUSTOMER-SCORE
    DISPLAY 'Processing Time: ' PROCESSING-TIME ' ms'
    DISPLAY ''
    DISPLAY 'External Data Updated:'
    DISPLAY 'Success Counter: ' SUCCESS-COUNTER
    DISPLAY 'Error Counter: ' ERROR-COUNTER
    DISPLAY 'Customers Processed: ' CUSTOMERS-PROCESSED
    DISPLAY 'Accounts Updated: ' ACCOUNTS-UPDATED
    DISPLAY 'Programs Called: ' PROGRAMS-CALLED.

Transaction Processing Subprogram

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IDENTIFICATION DIVISION.
PROGRAM-ID. TRANPROC.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
*> External data items - must match main program declarations
01  EXTERNAL-SYSTEM-CONTROL    EXTERNAL.
    05  SYSTEM-STATUS           PIC X(10).
    05  CURRENT-USER-ID         PIC X(8).
    05  SESSION-ID              PIC X(20).
    05  PROCESSING-MODE         PIC X(10).
    05  SYSTEM-DATE-TIME        PIC X(14).
    05  TRANSACTION-COUNTER     PIC 9(10).
    05  ERROR-COUNTER           PIC 9(5).
    05  SUCCESS-COUNTER         PIC 9(8).
 
01  EXTERNAL-BUSINESS-DATA     EXTERNAL.
    05  CURRENT-CUSTOMER.
        10  CUSTOMER-ID         PIC 9(8).
        10  CUSTOMER-NAME       PIC X(30).
        10  CUSTOMER-TYPE       PIC X(10).
        10  ACCOUNT-BALANCE     PIC 9(9)V99.
        10  CREDIT-LIMIT        PIC 9(9)V99.
        10  LAST-ACTIVITY-DATE  PIC 9(8).
    05  CURRENT-TRANSACTION.
        10  TRANSACTION-ID      PIC 9(10).
        10  TRANSACTION-TYPE    PIC X(10).
            88  DEPOSIT-TRANS   VALUE 'DEPOSIT'.
            88  WITHDRAWAL-TRANS VALUE 'WITHDRAWAL'.
            88  TRANSFER-TRANS  VALUE 'TRANSFER'.
            88  PAYMENT-TRANS   VALUE 'PAYMENT'.
        10  TRANSACTION-AMOUNT  PIC 9(9)V99.
        10  TRANSACTION-DATE    PIC 9(8).
        10  TRANSACTION-TIME    PIC 9(6).
        10  TRANSACTION-STATUS  PIC X(10).
            88  TRANS-PENDING   VALUE 'PENDING'.
            88  TRANS-COMPLETED VALUE 'COMPLETED'.
            88  TRANS-FAILED    VALUE 'FAILED'.
 
01  EXTERNAL-STATISTICS        EXTERNAL.
    05  PERFORMANCE-METRICS.
        10  TOTAL-TRANSACTIONS  PIC 9(10).
        10  SUCCESSFUL-TRANS    PIC 9(10).
        10  FAILED-TRANS        PIC 9(8).
    05  SYSTEM-METRICS.
        10  PROGRAMS-CALLED     PIC 9(6).
        10  IO-OPERATIONS       PIC 9(9).
    05  BUSINESS-METRICS.
        10  CUSTOMERS-PROCESSED PIC 9(8).
        10  ACCOUNTS-UPDATED    PIC 9(8).
 
*> Local working storage for transaction processing
01  LOCAL-TRANSACTION-VARIABLES.
    05  TRANSACTION-RESULT      PIC X(10) VALUE SPACES.
    05  AUTHORIZATION-CODE      PIC X(8) VALUE SPACES.
    05  PROCESSING-FEE          PIC 9(5)V99 VALUE 0.
    05  NEW-BALANCE             PIC 9(9)V99 VALUE 0.
    05  TRANSACTION-VALID       PIC X VALUE 'Y'.
        88  VALID-TRANSACTION   VALUE 'Y'.
        88  INVALID-TRANSACTION VALUE 'N'.
 
PROCEDURE DIVISION.
TRANSACTION-PROCESSING.
    DISPLAY 'Transaction Processing Subprogram Started'
    DISPLAY 'Processing transaction from external data...'
    
    PERFORM VALIDATE-TRANSACTION
    PERFORM PROCESS-TRANSACTION
    PERFORM UPDATE-TRANSACTION-STATISTICS
    PERFORM DISPLAY-TRANSACTION-RESULTS
    
    DISPLAY 'Transaction Processing Subprogram Completed'
    EXIT PROGRAM.
 
VALIDATE-TRANSACTION.
    DISPLAY 'Validating transaction...'
    
    *> Display current transaction from external data
    DISPLAY 'Transaction ID: ' TRANSACTION-ID
    DISPLAY 'Transaction Type: ' TRANSACTION-TYPE
    DISPLAY 'Transaction Amount: ' TRANSACTION-AMOUNT
    DISPLAY 'Current Balance: ' ACCOUNT-BALANCE
    
    *> Validate transaction
    IF TRANSACTION-AMOUNT > 0
        IF DEPOSIT-TRANS OR PAYMENT-TRANS
            SET VALID-TRANSACTION TO TRUE
            MOVE 'VALID' TO TRANSACTION-RESULT
        ELSE
            IF WITHDRAWAL-TRANS OR TRANSFER-TRANS
                IF TRANSACTION-AMOUNT <= ACCOUNT-BALANCE
                    SET VALID-TRANSACTION TO TRUE
                    MOVE 'VALID' TO TRANSACTION-RESULT
                ELSE
                    SET INVALID-TRANSACTION TO TRUE
                    MOVE 'INSUFFICIENT' TO TRANSACTION-RESULT
                    DISPLAY 'Insufficient funds for transaction'
                END-IF
            ELSE
                SET INVALID-TRANSACTION TO TRUE
                MOVE 'INVALID-TYPE' TO TRANSACTION-RESULT
                DISPLAY 'Invalid transaction type'
            END-IF
        END-IF
    ELSE
        SET INVALID-TRANSACTION TO TRUE
        MOVE 'INVALID-AMT' TO TRANSACTION-RESULT
        DISPLAY 'Invalid transaction amount'
    END-IF.
 
PROCESS-TRANSACTION.
    DISPLAY 'Processing transaction...'
    
    IF VALID-TRANSACTION
        *> Calculate processing fee
        IF DEPOSIT-TRANS
            MOVE 0 TO PROCESSING-FEE
        ELSE
            COMPUTE PROCESSING-FEE = TRANSACTION-AMOUNT * 0.001
            IF PROCESSING-FEE > 25.00
                MOVE 25.00 TO PROCESSING-FEE
            END-IF
        END-IF
        
        *> Process transaction based on type
        EVALUATE TRUE
            WHEN DEPOSIT-TRANS
                COMPUTE NEW-BALANCE = ACCOUNT-BALANCE + TRANSACTION-AMOUNT
                MOVE 'DEPOSIT-OK' TO AUTHORIZATION-CODE
                DISPLAY 'Deposit processed successfully'
            WHEN WITHDRAWAL-TRANS
                COMPUTE NEW-BALANCE = ACCOUNT-BALANCE - TRANSACTION-AMOUNT 
                                    - PROCESSING-FEE
                MOVE 'WITHDRAW-OK' TO AUTHORIZATION-CODE
                DISPLAY 'Withdrawal processed successfully'
            WHEN TRANSFER-TRANS
                COMPUTE NEW-BALANCE = ACCOUNT-BALANCE - TRANSACTION-AMOUNT 
                                    - PROCESSING-FEE
                MOVE 'TRANSFER-OK' TO AUTHORIZATION-CODE
                DISPLAY 'Transfer processed successfully'
            WHEN PAYMENT-TRANS
                COMPUTE NEW-BALANCE = ACCOUNT-BALANCE + TRANSACTION-AMOUNT
                MOVE 'PAYMENT-OK' TO AUTHORIZATION-CODE
                DISPLAY 'Payment processed successfully'
        END-EVALUATE
        
        *> Update external account balance
        MOVE NEW-BALANCE TO ACCOUNT-BALANCE
        SET TRANS-COMPLETED TO TRUE
        MOVE 'COMPLETED' TO TRANSACTION-RESULT
        
        *> Update counters
        ADD 1 TO TRANSACTION-COUNTER
        ADD 1 TO SUCCESS-COUNTER
        ADD 1 TO SUCCESSFUL-TRANS
        ADD 1 TO TOTAL-TRANSACTIONS
        
        DISPLAY 'New Balance: ' NEW-BALANCE
        DISPLAY 'Processing Fee: ' PROCESSING-FEE
        DISPLAY 'Authorization Code: ' AUTHORIZATION-CODE
    ELSE
        SET TRANS-FAILED TO TRUE
        ADD 1 TO ERROR-COUNTER
        ADD 1 TO FAILED-TRANS
        ADD 1 TO TOTAL-TRANSACTIONS
        DISPLAY 'Transaction processing failed'
    END-IF.
 
UPDATE-TRANSACTION-STATISTICS.
    DISPLAY 'Updating transaction statistics...'
    
    *> Update external statistics
    ADD 1 TO PROGRAMS-CALLED
    ADD 1 TO IO-OPERATIONS
    
    IF VALID-TRANSACTION
        ADD 1 TO ACCOUNTS-UPDATED
        DISPLAY 'Account updated successfully'
    END-IF
    
    DISPLAY 'Transaction Counter: ' TRANSACTION-COUNTER
    DISPLAY 'Success Counter: ' SUCCESS-COUNTER
    DISPLAY 'Error Counter: ' ERROR-COUNTER.
 
DISPLAY-TRANSACTION-RESULTS.
    DISPLAY 'Transaction Processing Results:'
    DISPLAY '=============================='
    DISPLAY 'Transaction Result: ' TRANSACTION-RESULT
    DISPLAY 'Authorization Code: ' AUTHORIZATION-CODE
    DISPLAY 'Processing Fee: ' PROCESSING-FEE
    DISPLAY 'New Balance: ' NEW-BALANCE
    DISPLAY 'Transaction Status: ' TRANSACTION-STATUS
    DISPLAY ''
    DISPLAY 'External Statistics Updated:'
    DISPLAY 'Total Transactions: ' TOTAL-TRANSACTIONS
    DISPLAY 'Successful Transactions: ' SUCCESSFUL-TRANS
    DISPLAY 'Failed Transactions: ' FAILED-TRANS
    DISPLAY 'Programs Called: ' PROGRAMS-CALLED
    DISPLAY 'Accounts Updated: ' ACCOUNTS-UPDATED.

Best Practices and FAQ

EXTERNAL Best Practices
  • • Use identical data definitions across programs
  • • Initialize external data in main program
  • • Document external data dependencies
  • • Use meaningful external data names
  • • Implement proper data validation
Data Sharing Guidelines
  • • Minimize external data complexity
  • • Use external data for system-wide state
  • • Implement consistent data access patterns
  • • Consider thread safety in multi-threaded environments
  • • Plan for data lifecycle management