What is CICS programming in COBOL?

CICS programming in COBOL involves developing interactive transaction processing applications using CICS (Customer Information Control System) commands and services for mainframe applications.

What are CICS commands in COBOL?

CICS commands are special statements that interface with the CICS system, including SEND, RECEIVE, READ, WRITE, XCTL, RETURN, and other transaction processing commands.

How do you handle CICS maps in COBOL?

CICS maps are handled using BMS (Basic Mapping Support) macros, map definitions, field attributes, and CICS commands like SEND MAP and RECEIVE MAP for screen handling.

What is transaction management in CICS?

Transaction management in CICS involves handling transaction IDs, program linking, resource management, and coordinating multiple programs within a single transaction.

How do you implement error handling in CICS COBOL?

Error handling in CICS COBOL is implemented using HANDLE conditions, RESP and RESP2 fields, error processing routines, and proper transaction cleanup procedures.

What are CICS program linkage techniques?

CICS program linkage techniques include XCTL (transfer control), LINK (call and return), RETURN (end transaction), and COBOL CALL statements for program communication.

MainframeMaster

COBOL CICS Programming

COBOL CICS programming enables the development of interactive transaction processing applications on mainframe systems. CICS (Customer Information Control System) provides a comprehensive environment for building online applications with screen handling, transaction management, and resource control capabilities.

Understanding CICS Programming

CICS programming combines COBOL with CICS commands to create interactive applications that can handle multiple users simultaneously. It provides transaction processing, screen management, database access, and program communication services.

CICS Program Structure

1. Basic CICS COBOL Program

A typical CICS COBOL program includes CICS commands, working storage, and transaction processing logic.

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. CICS-SAMPLE.
       ENVIRONMENT DIVISION.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 WS-CICS-FIELDS.
           05 WS-TRANID          PIC X(4) VALUE 'SAMP'.
           05 WS-MAPSET          PIC X(8) VALUE 'SAMPMAP'.
           05 WS-MAPNAME         PIC X(8) VALUE 'SAMP01'.
           05 WS-RESPONSE        PIC S9(8) COMP.
           05 WS-RESPONSE2       PIC S9(8) COMP.
       
       01 WS-COMMAREA.
           05 WS-FUNCTION        PIC X(1).
               88 WS-INITIAL     VALUE 'I'.
               88 WS-PROCESS     VALUE 'P'.
           05 WS-CUSTOMER-ID     PIC 9(6).
           05 WS-CUSTOMER-NAME   PIC X(30).
           05 WS-STATUS          PIC X(1).
       
       LINKAGE SECTION.
       01 DFHCOMMAREA.
           05 LK-FUNCTION        PIC X(1).
           05 LK-CUSTOMER-ID     PIC 9(6).
           05 LK-CUSTOMER-NAME   PIC X(30).
           05 LK-STATUS          PIC X(1).
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           EXEC CICS HANDLE CONDITION
               ERROR(ERROR-ROUTINE)
               END-EXEC
           
           EXEC CICS RECEIVE
               INTO(WS-COMMAREA)
               LENGTH(LENGTH OF WS-COMMAREA)
               RESP(WS-RESPONSE)
           END-EXEC
           
           IF WS-RESPONSE = DFHRESP(NORMAL)
               PERFORM PROCESS-TRANSACTION
           ELSE
               PERFORM ERROR-ROUTINE
           END-IF
           
           EXEC CICS RETURN
               TRANSID(WS-TRANID)
               COMMAREA(WS-COMMAREA)
               LENGTH(LENGTH OF WS-COMMAREA)
           END-EXEC.

2. CICS Map Handling

Handle CICS maps for screen input and output using BMS (Basic Mapping Support) and CICS commands.

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       WORKING-STORAGE SECTION.
       01 WS-MAP-FIELDS.
           05 WS-MAP-INPUT       PIC X(80).
           05 WS-MAP-OUTPUT      PIC X(80).
           05 WS-CURSOR-POS      PIC S9(4) COMP.
           05 WS-MAP-LENGTH      PIC S9(4) COMP VALUE 80.
       
       PROCEDURE DIVISION.
       HANDLE-MAP-INPUT.
           EXEC CICS RECEIVE MAP(WS-MAPNAME)
               MAPSET(WS-MAPSET)
               INTO(WS-MAP-INPUT)
               LENGTH(WS-MAP-LENGTH)
               RESP(WS-RESPONSE)
           END-EXEC
           
           IF WS-RESPONSE = DFHRESP(NORMAL)
               PERFORM PROCESS-MAP-DATA
           ELSE
               IF WS-RESPONSE = DFHRESP(MAPFAIL)
                   PERFORM SEND-INITIAL-MAP
               ELSE
                   PERFORM ERROR-ROUTINE
               END-IF
           END-IF.
       
       SEND-MAP-OUTPUT.
           EXEC CICS SEND MAP(WS-MAPNAME)
               MAPSET(WS-MAPSET)
               FROM(WS-MAP-OUTPUT)
               LENGTH(WS-MAP-LENGTH)
               CURSOR(WS-CURSOR-POS)
               ERASE
           END-EXEC.
       
       SEND-INITIAL-MAP.
           EXEC CICS SEND MAP(WS-MAPNAME)
               MAPSET(WS-MAPSET)
               FROM(WS-MAP-OUTPUT)
               LENGTH(WS-MAP-LENGTH)
               ERASE
           END-EXEC.

3. CICS File Operations

Perform file operations using CICS commands for reading, writing, and updating data files.

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       WORKING-STORAGE SECTION.
       01 WS-FILE-CONTROL.
           05 WS-FILE-NAME       PIC X(8) VALUE 'CUSTFILE'.
           05 WS-RECORD-KEY      PIC X(6).
           05 WS-RECORD-LENGTH   PIC S9(4) COMP VALUE 100.
       
       01 WS-CUSTOMER-RECORD.
           05 WS-CUST-ID         PIC 9(6).
           05 WS-CUST-NAME       PIC X(30).
           05 WS-CUST-ADDRESS    PIC X(50).
           05 WS-CUST-PHONE      PIC X(12).
           05 WS-CUST-BALANCE    PIC 9(8)V99.
       
       PROCEDURE DIVISION.
       READ-CUSTOMER-RECORD.
           EXEC CICS READ
               FILE(WS-FILE-NAME)
               INTO(WS-CUSTOMER-RECORD)
               LENGTH(WS-RECORD-LENGTH)
               RIDFLD(WS-RECORD-KEY)
               RESP(WS-RESPONSE)
           END-EXEC
           
           EVALUATE WS-RESPONSE
               WHEN DFHRESP(NORMAL)
                   PERFORM PROCESS-CUSTOMER-DATA
               WHEN DFHRESP(NOTFND)
                   PERFORM CUSTOMER-NOT-FOUND
               WHEN OTHER
                   PERFORM FILE-ERROR-ROUTINE
           END-EVALUATE.
       
       WRITE-CUSTOMER-RECORD.
           EXEC CICS WRITE
               FILE(WS-FILE-NAME)
               FROM(WS-CUSTOMER-RECORD)
               LENGTH(WS-RECORD-LENGTH)
               RIDFLD(WS-RECORD-KEY)
               RESP(WS-RESPONSE)
           END-EXEC
           
           IF WS-RESPONSE NOT = DFHRESP(NORMAL)
               PERFORM FILE-ERROR-ROUTINE
           END-IF.

CICS Transaction Management

1. Program Linkage

Implement program linkage using XCTL, LINK, and RETURN commands for program communication and control transfer.

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       PROCEDURE DIVISION.
       TRANSFER-CONTROL.
           EXEC CICS XCTL
               PROGRAM('NEXT-PROGRAM')
               COMMAREA(WS-COMMAREA)
               LENGTH(LENGTH OF WS-COMMAREA)
               RESP(WS-RESPONSE)
           END-EXEC
           
           IF WS-RESPONSE NOT = DFHRESP(NORMAL)
               PERFORM XCTL-ERROR-ROUTINE
           END-IF.
       
       CALL-SUBPROGRAM.
           EXEC CICS LINK
               PROGRAM('SUB-PROGRAM')
               COMMAREA(WS-COMMAREA)
               LENGTH(LENGTH OF WS-COMMAREA)
               RESP(WS-RESPONSE)
           END-EXEC
           
           IF WS-RESPONSE NOT = DFHRESP(NORMAL)
               PERFORM LINK-ERROR-ROUTINE
           END-IF.
       
       END-TRANSACTION.
           EXEC CICS RETURN
               TRANSID(WS-TRANID)
               COMMAREA(WS-COMMAREA)
               LENGTH(LENGTH OF WS-COMMAREA)
           END-EXEC.

2. Error Handling

Implement comprehensive error handling using CICS HANDLE conditions and response code checking.

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       PROCEDURE DIVISION.
       SETUP-ERROR-HANDLING.
           EXEC CICS HANDLE CONDITION
               ERROR(ERROR-ROUTINE)
               MAPFAIL(MAPFAIL-ROUTINE)
               NOTFND(NOTFOUND-ROUTINE)
               DUPREC(DUPLICATE-ROUTINE)
           END-EXEC.
       
       ERROR-ROUTINE.
           MOVE 'E' TO WS-STATUS
           MOVE 'SYSTEM ERROR OCCURRED' TO WS-ERROR-MESSAGE
           PERFORM SEND-ERROR-MESSAGE
           EXEC CICS RETURN
               TRANSID(WS-TRANID)
               COMMAREA(WS-COMMAREA)
               LENGTH(LENGTH OF WS-COMMAREA)
           END-EXEC.
       
       MAPFAIL-ROUTINE.
           MOVE 'M' TO WS-STATUS
           MOVE 'INVALID MAP DATA' TO WS-ERROR-MESSAGE
           PERFORM SEND-ERROR-MESSAGE
           PERFORM SEND-INITIAL-MAP.
       
       NOTFOUND-ROUTINE.
           MOVE 'N' TO WS-STATUS
           MOVE 'RECORD NOT FOUND' TO WS-ERROR-MESSAGE
           PERFORM SEND-ERROR-MESSAGE.
       
       DUPLICATE-ROUTINE.
           MOVE 'D' TO WS-STATUS
           MOVE 'DUPLICATE RECORD' TO WS-ERROR-MESSAGE
           PERFORM SEND-ERROR-MESSAGE.

3. Resource Management

Manage CICS resources including temporary storage, transient data, and program resources.

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       WORKING-STORAGE SECTION.
       01 WS-TEMP-STORAGE.
           05 WS-TS-QUEUE        PIC X(8) VALUE 'TEMPQUE'.
           05 WS-TS-LENGTH       PIC S9(4) COMP.
           05 WS-TS-DATA         PIC X(100).
       
       PROCEDURE DIVISION.
       WRITE-TEMP-STORAGE.
           EXEC CICS WRITEQ TS
               QUEUE(WS-TS-QUEUE)
               FROM(WS-TS-DATA)
               LENGTH(WS-TS-LENGTH)
               RESP(WS-RESPONSE)
           END-EXEC
           
           IF WS-RESPONSE NOT = DFHRESP(NORMAL)
               PERFORM TEMP-STORAGE-ERROR
           END-IF.
       
       READ-TEMP-STORAGE.
           EXEC CICS READQ TS
               QUEUE(WS-TS-QUEUE)
               INTO(WS-TS-DATA)
               LENGTH(WS-TS-LENGTH)
               RESP(WS-RESPONSE)
           END-EXEC
           
           EVALUATE WS-RESPONSE
               WHEN DFHRESP(NORMAL)
                   PERFORM PROCESS-TEMP-DATA
               WHEN DFHRESP(QIDERR)
                   PERFORM QUEUE-EMPTY-ROUTINE
               WHEN OTHER
                   PERFORM TEMP-STORAGE-ERROR
           END-EVALUATE.

Best Practices for CICS Programming

Error Handling: Always implement comprehensive error handling
Resource Management: Properly manage CICS resources
Performance: Optimize for transaction throughput
Security: Implement proper security controls
Testing: Test all error conditions and scenarios
Documentation: Document CICS program interfaces and logic

Common CICS Programming Patterns

Menu Processing: Handle menu selection and navigation
Data Entry: Process user input and validation
Inquiry Processing: Handle data retrieval and display
Update Processing: Handle data modification operations
Report Generation: Generate and display reports
Batch Interface: Interface with batch processing systems

COBOL CICS Programming

Understanding CICS Programming

CICS Program Structure

1. Basic CICS COBOL Program

2. CICS Map Handling

3. CICS File Operations

CICS Transaction Management

1. Program Linkage

2. Error Handling

3. Resource Management

Best Practices for CICS Programming

Common CICS Programming Patterns

Transaction Processing

Interactive Programming

Screen Handling

Program Communication

Error Handling

Resource Management