What is data sharing in COBOL?

The process of sharing data between programs using shared data areas, common storage, program parameters, and communication mechanisms for coordinated data access and processing.

What are shared data areas?

Memory areas that can be accessed by multiple programs simultaneously, allowing programs to share information and coordinate their operations in a mainframe environment.

How do programs share data?

Through shared data areas, program parameters, common storage, file-based communication, and messaging systems that enable data exchange between different programs.

MainframeMaster

COBOL Data Sharing

Data sharing enables programs to exchange information and coordinate operations through shared data areas, program parameters, and communication mechanisms. Learn techniques for effective data sharing in mainframe environments.

Shared Data Areas

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       WORKING-STORAGE SECTION.
       01 SHARED-DATA-AREA.
           05 SHARED-CUSTOMER-DATA.
               10 SHARED-CUSTOMER-ID PIC 9(6).
               10 SHARED-CUSTOMER-NAME PIC X(30).
               10 SHARED-CUSTOMER-BALANCE PIC 9(9)V99.
               10 SHARED-CUSTOMER-STATUS PIC X.
                   88 SHARED-CUSTOMER-ACTIVE VALUE 'A'.
                   88 SHARED-CUSTOMER-INACTIVE VALUE 'I'.
           05 SHARED-TRANSACTION-DATA.
               10 SHARED-TRANSACTION-ID PIC 9(8).
               10 SHARED-TRANSACTION-AMOUNT PIC 9(9)V99.
               10 SHARED-TRANSACTION-DATE PIC 9(8).
           05 SHARED-CONTROL-DATA.
               10 SHARED-PROCESSING-FLAG PIC X.
               10 SHARED-ERROR-CODE PIC 9(3).
               10 SHARED-MESSAGE PIC X(50).
       
       PROCEDURE DIVISION.
       PERFORM DEMONSTRATE-SHARED-DATA-AREA
       
       DEMONSTRATE-SHARED-DATA-AREA.
           MOVE 123456 TO SHARED-CUSTOMER-ID
           MOVE 'JOHN SMITH' TO SHARED-CUSTOMER-NAME
           MOVE 1500.50 TO SHARED-CUSTOMER-BALANCE
           MOVE 'A' TO SHARED-CUSTOMER-STATUS
           
           MOVE 87654321 TO SHARED-TRANSACTION-ID
           MOVE 500.00 TO SHARED-TRANSACTION-AMOUNT
           MOVE 20231225 TO SHARED-TRANSACTION-DATE
           
           MOVE 'Y' TO SHARED-PROCESSING-FLAG
           MOVE 0 TO SHARED-ERROR-CODE
           MOVE 'DATA SHARED SUCCESSFULLY' TO SHARED-MESSAGE
           
           DISPLAY 'Shared Data Area demonstration:'
           DISPLAY 'Customer ID: ' SHARED-CUSTOMER-ID
           DISPLAY 'Customer Name: ' SHARED-CUSTOMER-NAME
           DISPLAY 'Customer Balance: ' SHARED-CUSTOMER-BALANCE
           DISPLAY 'Transaction ID: ' SHARED-TRANSACTION-ID
           DISPLAY 'Transaction Amount: ' SHARED-TRANSACTION-AMOUNT
           DISPLAY 'Processing Flag: ' SHARED-PROCESSING-FLAG
           DISPLAY 'Message: ' SHARED-MESSAGE.

Shared data areas provide common storage that can be accessed by multiple programs. Define shared data structures with clear organization and use appropriate data types for reliable data sharing.

Program Parameter Sharing

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       LINKAGE SECTION.
       01 PROGRAM-PARAMETERS.
           05 INPUT-PARAMETERS.
               10 INPUT-CUSTOMER-ID PIC 9(6).
               10 INPUT-TRANSACTION-AMOUNT PIC 9(9)V99.
               10 INPUT-OPERATION-TYPE PIC X.
           05 OUTPUT-PARAMETERS.
               10 OUTPUT-RETURN-CODE PIC 9(4).
               10 OUTPUT-MESSAGE PIC X(50).
               10 OUTPUT-NEW-BALANCE PIC 9(9)V99.
           05 SHARED-PARAMETERS.
               10 SHARED-SESSION-ID PIC X(10).
               10 SHARED-USER-ID PIC X(8).
               10 SHARED-TIMESTAMP PIC 9(14).
       
       PROCEDURE DIVISION USING PROGRAM-PARAMETERS.
       PERFORM DEMONSTRATE-PARAMETER-SHARING
       
       DEMONSTRATE-PARAMETER-SHARING.
           DISPLAY 'Program Parameter Sharing demonstration:'
           DISPLAY 'Input Customer ID: ' INPUT-CUSTOMER-ID
           DISPLAY 'Input Transaction Amount: ' INPUT-TRANSACTION-AMOUNT
           DISPLAY 'Input Operation Type: ' INPUT-OPERATION-TYPE
           DISPLAY 'Shared Session ID: ' SHARED-SESSION-ID
           DISPLAY 'Shared User ID: ' SHARED-USER-ID
           DISPLAY 'Shared Timestamp: ' SHARED-TIMESTAMP
           
           MOVE 0 TO OUTPUT-RETURN-CODE
           MOVE 'PROCESSING COMPLETED' TO OUTPUT-MESSAGE
           MOVE 2000.50 TO OUTPUT-NEW-BALANCE
           
           DISPLAY 'Output Return Code: ' OUTPUT-RETURN-CODE
           DISPLAY 'Output Message: ' OUTPUT-MESSAGE
           DISPLAY 'Output New Balance: ' OUTPUT-NEW-BALANCE.

Use program parameters to share data between calling and called programs. Define input parameters for data passed to the program, output parameters for results returned, and shared parameters for common data.

Common Storage Areas

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       WORKING-STORAGE SECTION.
       01 COMMON-STORAGE-AREA.
           05 COMMON-CUSTOMER-DATA.
               10 COMMON-CUSTOMER-ID PIC 9(6).
               10 COMMON-CUSTOMER-NAME PIC X(30).
               10 COMMON-CUSTOMER-BALANCE PIC 9(9)V99.
           05 COMMON-TRANSACTION-DATA.
               10 COMMON-TRANSACTION-ID PIC 9(8).
               10 COMMON-TRANSACTION-AMOUNT PIC 9(9)V99.
               10 COMMON-TRANSACTION-DATE PIC 9(8).
           05 COMMON-CONTROL-INFO.
               10 COMMON-PROCESSING-STATUS PIC X.
               10 COMMON-ERROR-COUNT PIC 9(3).
               10 COMMON-LAST-UPDATE PIC 9(14).
       
       PROCEDURE DIVISION.
       PERFORM DEMONSTRATE-COMMON-STORAGE
       
       DEMONSTRATE-COMMON-STORAGE.
           MOVE 123456 TO COMMON-CUSTOMER-ID
           MOVE 'JANE DOE' TO COMMON-CUSTOMER-NAME
           MOVE 2500.75 TO COMMON-CUSTOMER-BALANCE
           
           MOVE 98765432 TO COMMON-TRANSACTION-ID
           MOVE 750.25 TO COMMON-TRANSACTION-AMOUNT
           MOVE 20231225 TO COMMON-TRANSACTION-DATE
           
           MOVE 'A' TO COMMON-PROCESSING-STATUS
           MOVE 0 TO COMMON-ERROR-COUNT
           MOVE FUNCTION CURRENT-TIME TO COMMON-LAST-UPDATE
           
           DISPLAY 'Common Storage Area demonstration:'
           DISPLAY 'Common Customer ID: ' COMMON-CUSTOMER-ID
           DISPLAY 'Common Customer Name: ' COMMON-CUSTOMER-NAME
           DISPLAY 'Common Customer Balance: ' COMMON-CUSTOMER-BALANCE
           DISPLAY 'Common Transaction ID: ' COMMON-TRANSACTION-ID
           DISPLAY 'Common Processing Status: ' COMMON-PROCESSING-STATUS
           DISPLAY 'Common Error Count: ' COMMON-ERROR-COUNT.

Common storage areas provide persistent data that can be accessed by multiple programs in the same run unit. Use common storage for data that needs to persist across program calls and be shared between programs.

File-Based Data Sharing

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       FILE SECTION.
       FD SHARED-DATA-FILE
           LABEL RECORDS ARE STANDARD
           RECORDING MODE IS F.
       01 SHARED-DATA-RECORD.
           05 SHARED-RECORD-TYPE PIC X.
           05 SHARED-RECORD-DATA PIC X(99).
       
       WORKING-STORAGE SECTION.
       01 FILE-SHARING-CONTROL.
           05 FILE-SHARING-STATUS PIC X(2).
           05 FILE-SHARING-RECORD-COUNT PIC 9(6) VALUE 0.
           05 FILE-SHARING-LAST-UPDATE PIC 9(14).
       
       PROCEDURE DIVISION.
       PERFORM DEMONSTRATE-FILE-SHARING
       
       DEMONSTRATE-FILE-SHARING.
           OPEN I-O SHARED-DATA-FILE
           
           MOVE 'C' TO SHARED-RECORD-TYPE
           MOVE 'CUSTOMER DATA RECORD' TO SHARED-RECORD-DATA
           WRITE SHARED-DATA-RECORD
           
           MOVE 'T' TO SHARED-RECORD-TYPE
           MOVE 'TRANSACTION DATA RECORD' TO SHARED-RECORD-DATA
           WRITE SHARED-DATA-RECORD
           
           ADD 2 TO FILE-SHARING-RECORD-COUNT
           MOVE FUNCTION CURRENT-TIME TO FILE-SHARING-LAST-UPDATE
           
           DISPLAY 'File-based Data Sharing demonstration:'
           DISPLAY 'File Sharing Status: ' FILE-SHARING-STATUS
           DISPLAY 'Record Count: ' FILE-SHARING-RECORD-COUNT
           DISPLAY 'Last Update: ' FILE-SHARING-LAST-UPDATE
           
           CLOSE SHARED-DATA-FILE.

Use files for data sharing between programs that don't run in the same address space. Create shared data files with standardized record formats for reliable data exchange across different program executions.

Message-Based Data Sharing

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       WORKING-STORAGE SECTION.
       01 MESSAGE-SHARING-DATA.
           05 MESSAGE-HEADER.
               10 MESSAGE-TYPE PIC X(10).
               10 MESSAGE-LENGTH PIC 9(4).
               10 MESSAGE-SEQUENCE PIC 9(6).
               10 MESSAGE-TIMESTAMP PIC 9(14).
           05 MESSAGE-BODY.
               10 MESSAGE-CUSTOMER-ID PIC 9(6).
               10 MESSAGE-CUSTOMER-NAME PIC X(30).
               10 MESSAGE-TRANSACTION-AMOUNT PIC 9(9)V99.
               10 MESSAGE-OPERATION PIC X(10).
           05 MESSAGE-CONTROL.
               10 MESSAGE-STATUS PIC X.
               10 MESSAGE-ERROR-CODE PIC 9(3).
               10 MESSAGE-RESPONSE PIC X(50).
       
       PROCEDURE DIVISION.
       PERFORM DEMONSTRATE-MESSAGE-SHARING
       
       DEMONSTRATE-MESSAGE-SHARING.
           MOVE 'CUSTOMER' TO MESSAGE-TYPE
           MOVE 60 TO MESSAGE-LENGTH
           MOVE 1 TO MESSAGE-SEQUENCE
           MOVE FUNCTION CURRENT-TIME TO MESSAGE-TIMESTAMP
           
           MOVE 123456 TO MESSAGE-CUSTOMER-ID
           MOVE 'JOHN SMITH' TO MESSAGE-CUSTOMER-NAME
           MOVE 1500.50 TO MESSAGE-TRANSACTION-AMOUNT
           MOVE 'DEPOSIT' TO MESSAGE-OPERATION
           
           MOVE 'P' TO MESSAGE-STATUS
           MOVE 0 TO MESSAGE-ERROR-CODE
           MOVE 'MESSAGE PROCESSED' TO MESSAGE-RESPONSE
           
           DISPLAY 'Message-based Data Sharing demonstration:'
           DISPLAY 'Message Type: ' MESSAGE-TYPE
           DISPLAY 'Message Length: ' MESSAGE-LENGTH
           DISPLAY 'Message Sequence: ' MESSAGE-SEQUENCE
           DISPLAY 'Customer ID: ' MESSAGE-CUSTOMER-ID
           DISPLAY 'Customer Name: ' MESSAGE-CUSTOMER-NAME
           DISPLAY 'Transaction Amount: ' MESSAGE-TRANSACTION-AMOUNT
           DISPLAY 'Operation: ' MESSAGE-OPERATION
           DISPLAY 'Message Status: ' MESSAGE-STATUS
           DISPLAY 'Response: ' MESSAGE-RESPONSE.

Implement message-based data sharing using structured message formats with headers, body, and control information. Use message queues or communication mechanisms for asynchronous data sharing between programs.

Data Sharing Synchronization

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       WORKING-STORAGE SECTION.
       01 SYNCHRONIZATION-CONTROL.
           05 LOCK-CONTROL.
               10 LOCK-STATUS PIC X.
                   88 LOCK-ACQUIRED VALUE 'Y'.
                   88 LOCK-NOT-ACQUIRED VALUE 'N'.
               10 LOCK-TIMEOUT PIC 9(3) VALUE 30.
               10 LOCK-RETRY-COUNT PIC 9(3) VALUE 0.
           05 SHARED-RESOURCE-CONTROL.
               10 RESOURCE-BUSY PIC X.
                   88 RESOURCE-AVAILABLE VALUE 'N'.
                   88 RESOURCE-BUSY VALUE 'Y'.
               10 RESOURCE-WAIT-TIME PIC 9(3) VALUE 5.
               10 RESOURCE-MAX-WAIT PIC 9(3) VALUE 60.
       
       PROCEDURE DIVISION.
       PERFORM DEMONSTRATE-SYNCHRONIZATION
       
       DEMONSTRATE-SYNCHRONIZATION.
           DISPLAY 'Data Sharing Synchronization demonstration:'
           
           *> Attempt to acquire lock
           PERFORM ACQUIRE-LOCK
           
           IF LOCK-ACQUIRED
               DISPLAY 'Lock acquired successfully'
               PERFORM ACCESS-SHARED-RESOURCE
               PERFORM RELEASE-LOCK
           ELSE
               DISPLAY 'Lock acquisition failed'
               PERFORM HANDLE-LOCK-FAILURE
           END-IF.
       
       ACQUIRE-LOCK.
           MOVE 'N' TO LOCK-STATUS
           MOVE 0 TO LOCK-RETRY-COUNT
           
           PERFORM UNTIL LOCK-ACQUIRED OR LOCK-RETRY-COUNT > 3
               ADD 1 TO LOCK-RETRY-COUNT
               *> Simulate lock acquisition logic
               IF RESOURCE-AVAILABLE
                   MOVE 'Y' TO LOCK-STATUS
                   MOVE 'Y' TO RESOURCE-BUSY
               ELSE
                   DISPLAY 'Resource busy, waiting...'
                   PERFORM WAIT-FOR-RESOURCE
               END-IF
           END-PERFORM.

Implement synchronization mechanisms for data sharing including lock acquisition, resource control, timeout handling, and retry logic to ensure safe concurrent access to shared data.

Data Sharing Error Handling

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       WORKING-STORAGE SECTION.
       01 SHARING-ERROR-HANDLING.
           05 ERROR-CONTROL.
               10 SHARING-ERROR-COUNT PIC 9(3) VALUE 0.
               10 MAX-SHARING-ERRORS PIC 9(3) VALUE 10.
               10 SHARING-ERROR-THRESHOLD PIC 9(3) VALUE 5.
           05 ERROR-TYPES.
               10 LOCK-TIMEOUT-ERROR PIC 9(3) VALUE 0.
               10 DATA-CORRUPTION-ERROR PIC 9(3) VALUE 0.
               10 COMMUNICATION-ERROR PIC 9(3) VALUE 0.
               10 VALIDATION-ERROR PIC 9(3) VALUE 0.
           05 ERROR-RESPONSES.
               10 ERROR-RECOVERY-ACTION PIC X(20).
               10 ERROR-NOTIFICATION PIC X(50).
               10 ERROR-LOG-ENTRY PIC X(100).
       
       PROCEDURE DIVISION.
       PERFORM DEMONSTRATE-ERROR-HANDLING
       
       DEMONSTRATE-ERROR-HANDLING.
           DISPLAY 'Data Sharing Error Handling demonstration:'
           
           *> Simulate different error conditions
           PERFORM SIMULATE-LOCK-TIMEOUT
           PERFORM SIMULATE-DATA-CORRUPTION
           PERFORM SIMULATE-COMMUNICATION-ERROR
           
           DISPLAY 'Error Handling Results:'
           DISPLAY 'Total Errors: ' SHARING-ERROR-COUNT
           DISPLAY 'Lock Timeout Errors: ' LOCK-TIMEOUT-ERROR
           DISPLAY 'Data Corruption Errors: ' DATA-CORRUPTION-ERROR
           DISPLAY 'Communication Errors: ' COMMUNICATION-ERROR
           DISPLAY 'Validation Errors: ' VALIDATION-ERROR.
       
       SIMULATE-LOCK-TIMEOUT.
           ADD 1 TO LOCK-TIMEOUT-ERROR
           ADD 1 TO SHARING-ERROR-COUNT
           MOVE 'RETRY WITH BACKOFF' TO ERROR-RECOVERY-ACTION
           MOVE 'Lock timeout occurred' TO ERROR-NOTIFICATION.

Implement comprehensive error handling for data sharing operations including error counting, categorization, recovery actions, and notification mechanisms to ensure reliable data sharing.

Data Sharing Performance

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       WORKING-STORAGE SECTION.
       01 SHARING-PERFORMANCE-METRICS.
           05 PERFORMANCE-METRICS.
               10 SHARING-OPERATION-COUNT PIC 9(8) VALUE 0.
               10 SHARING-RESPONSE-TIME PIC 9(6).
               10 SHARING-THROUGHPUT PIC 9(6).
               10 SHARING-ERROR-RATE PIC 9(3)V99.
           05 OPTIMIZATION-CONTROL.
               10 BATCH-SIZE PIC 9(4) VALUE 100.
               10 CACHE-SIZE PIC 9(6) VALUE 1000.
               10 BUFFER-SIZE PIC 9(6) VALUE 10000.
           05 PERFORMANCE-TARGETS.
               10 TARGET-RESPONSE-TIME PIC 9(6) VALUE 1000.
               10 TARGET-THROUGHPUT PIC 9(6) VALUE 1000.
               10 TARGET-ERROR-RATE PIC 9(3)V99 VALUE 1.00.
       
       PROCEDURE DIVISION.
       PERFORM DEMONSTRATE-PERFORMANCE-MONITORING
       
       DEMONSTRATE-PERFORMANCE-MONITORING.
           MOVE FUNCTION CURRENT-TIME TO START-TIME
           
           *> Perform sharing operations
           PERFORM SHARING-OPERATIONS
           
           MOVE FUNCTION CURRENT-TIME TO END-TIME
           COMPUTE SHARING-RESPONSE-TIME = END-TIME - START-TIME
           COMPUTE SHARING-THROUGHPUT = SHARING-OPERATION-COUNT / SHARING-RESPONSE-TIME
           
           DISPLAY 'Data Sharing Performance Metrics:'
           DISPLAY 'Operation Count: ' SHARING-OPERATION-COUNT
           DISPLAY 'Response Time: ' SHARING-RESPONSE-TIME ' ms'
           DISPLAY 'Throughput: ' SHARING-THROUGHPUT ' ops/sec'
           DISPLAY 'Error Rate: ' SHARING-ERROR-RATE '%'
           DISPLAY 'Batch Size: ' BATCH-SIZE
           DISPLAY 'Cache Size: ' CACHE-SIZE
           DISPLAY 'Buffer Size: ' BUFFER-SIZE.

Monitor and optimize data sharing performance using metrics like response time, throughput, error rates, and resource utilization. Implement batching, caching, and buffering for improved performance.

Implement shared data areas for common program data access.
Use program parameters for data exchange between programs.
Apply synchronization mechanisms for safe concurrent access.
Handle data sharing errors with comprehensive error management.
Monitor performance metrics for optimal data sharing operations.

Data Sections

Working Storage and File Sections

Program Communication

Program communication techniques