CICS Error Handling Management

Comprehensive error handling is critical for building reliable CICS applications. This includes proper response code checking, ab-end management, condition handlers, and graceful degradation strategies.

Understanding CICS Response Codes

Response Code Structure

All CICS commands return response information through RESP and RESP2 parameters:

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WORKING-STORAGE SECTION.
01 WS-CICS-RESPONSE.
    02 WS-RESPONSE PIC S9(8) COMP.
    02 WS-RESPONSE2 PIC S9(8) COMP.
 
PROCEDURE DIVISION.
STANDARD-CICS-COMMAND.
    EXEC CICS READ FILE('CUSTOMER')
        INTO(WS-CUSTOMER-RECORD)
        RIDFLD(WS-CUSTOMER-ID)
        RESP(WS-RESPONSE)
        RESP2(WS-RESPONSE2)
    END-EXEC.

Common Response Codes

Code	Response	Meaning	Action
0	NORMAL	Operation successful	Continue processing
16	INVREQ	Invalid request	Check parameters
20	NOTFND	Resource not found	Handle missing resource
22	LENGERR	Length error	Adjust data length
24	RESUME	Resume state	Handle resume condition

Condition Handlers

HANDLE CONDITION

Use HANDLE CONDITION for specific error management:

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CONDITION-HANDLER-PATTERN.
    * Define condition handlers
    EXEC CICS HANDLE CONDITION
        LENGERR(ERROR-LENGTH-ERROR)
        NOTFND(ERROR-NOT-FOUND)
        FILEERR(ERROR-FILE-ERROR)
        END(ERROR-FILE-END)
        ENDFILE(ERROR-FILE-END)
    END-EXEC.
    
    * Protected code section
    EXEC CICS READ FILE('CUSTOMER')
        INTO(WS-CUSTOMER-RECORD)
        RIDFLD(WS-CUSTOMER-ID)
    END-EXEC.
    
    * Normal processing continues...
    PERFORM PROCESS-CUSTOMER-DATA
    EXEC CICS RETURN END-EXEC.
    
ERROR-LENGTH-ERROR.
    DISPLAY 'ERROR: Data length exceeded maximum'
    PERFORM LOG-ERROR-DETAILS
    PERFORM SEND-ERROR-TO-USER
    EXEC CICS RETURN END-EXEC.
    
ERROR-NOT-FOUND.
    DISPLAY 'ERROR: Customer not found'
    PERFORM LOG-CUSTOMER-NOT-FOUND
    PERFORM HANDLE-MISSING-CUSTOMER
    EXEC CICS RETURN END-EXEC.
    
ERROR-FILE-ERROR.
    DISPLAY 'ERROR: File access failed'
    PERFORM LOG-FILE-ERROR
    PERFORM HANDLE-FILE-FAILURE
    EXEC CICS RETURN END-EXEC.
    
ERROR-FILE-END.
    DISPLAY 'SUCCESS: File exhausted'
    PERFORM HANDLE-FILE-EXHAUSTED
    EXEC CICS RETURN END-EXEC.

HANDLE ABEND

Handle severe errors that cause ab-ends:

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ABEND-HANDLER-PATTERN.
    * Identify ab-end handler label
    EXEC CICS HANDLE ABEND LABEL(ABEND-EXIT-ONLY)
        RESP(WS-RESPONSE)
    END-EXEC.
    
    * Perform risky operation
    PERFORM HIGH-RISK-DATABASE-OPERATION
    
    * Normal completion
    EXEC CICS RETURN END-EXEC.
    
ABEND-EXIT-ONLY.
    * Retrieve ab-end information
    EXEC CICS ASSIGN ABEND-INFO(WS-ABEND-TIME)
        RESP(WS-RESPONSE)
    END-EXEC.
    
    * Log ab-end details
    PERFORM LOG-ABEND-INFORMATION
    PERFORM CLEANUP-FROM-ABEND
    PERFORM NOTIFY-OPERATIONS-TEAM
    
    * Terminate gracefully
    EXEC CICS RETURN ABEND END-EXEC.

Error Recovery Strategies

Immediate Recovery

Handle errors that can be resolved immediately:

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IMMEDIATE-RECOVERY-PATTERN.
    PERFORM ATTEMPT-CRITICAL-OPERATION
    
    IF WS-RESPONSE NOT = DFHRESP(NORMAL)
        PERFORM LOG-OPERATION-FAILURE
        
        * Attempt immediate recovery
        PERFORM ATTEMPT-RECOVERY-ACTION
        
        IF WS-RECOVERY-SUCCESSFUL = 'Y'
            PERFORM CONTINUE-PROCESSING
        ELSE
            PERFORM GRACEFUL-DEGRADATION
        END-IF
    END-IF.

Retry Logic

Implement retry mechanisms for transient failures:

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RETRY-LOGIC-PATTERN.
    MOVE ZERO TO WS-RETRY-COUNT
    SET WS-OPERATION-SUCCESSFUL TO FALSE
    
    PERFORM UNTIL WS-OPERATION-SUCCESSFUL OR WS-MAX-RETRIES-REACHED
        ADD 1 TO WS-RETRY-COUNT
        
        PERFORM ATTEMPT-OPERATION
        
        EVALUATE WS-RESPONSE
            WHEN DFHRESP(NORMAL)
                SET WS-OPERATION-SUCCESSFUL TO TRUE
            WHEN DFHRESP(COMMFAIL)
            WHEN DFHRESP(SESSERR)
                IF WS-RETRY-COUNT < MAX-RETRY-ATTEMPTS
                    PERFORM WAIT-BETWEEN-RETRIES
                ELSE
                    PERFORM ABORT-RETRY-ATTEMPTS
                END-IF
            WHEN OTHER
                PERFORM ABORT-RETRY-ATTEMPTS
        END-EVALUATE
    END-PERFORM.

Error Logging and Monitoring

Centralized Error Logging

Implement comprehensive error logging:

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WORKING-STORAGE SECTION.
01 WS-ERROR-LOG-ENTRY.
    02 WS-LOG-TIMESTAMP PIC X(26).
    02 WS-LOG-SEVERITY PIC X(10).
    02 WS-LOG-TRANSID PIC X(4).
    02 WS-LOG-PROGRAM PIC X(8).
    02 WS-LOG-ERROR-CODE PIC S9(8) COMP.
    02 WS-LOG-RETURN-CODE PIC S9(8) COMP.
    02 WS-LOG-RETURN-CODE2 PIC S9(8) COMP.
    02 WS-LOG-ERROR-MESSAGE PIC X(100).
 
PROCEDURE DIVISION.
CENTRALIZED-ERROR-LOGGING.
    PERFORM GET-CURRENT-TIME
    PERFORM LOG-CURRENT-FAUTRE-TIME-OF-DAY
    
    IF WS-ABEND-AVAILABLE = 'Y'
        PERFORM LOG-ABEND-INFORMATION
    END-IF
    
    PERFORM LOG-RETURN-CODES
    PERFORM LOG-GENERAL-PROGRAM-ERROR
    
CHECK-ERROR-TYPE.
    IF WS-RESPONSE = DFHRESP(IOERR)
        PERFORM LOG-IO-ERROR-DETAILS
    ELSE
        IF WS-RESPONSE NOT = DFHRESP(NORMAL)
            PERFORM LOG-GENERAL-CICS-ERROR
        END-IF
    END-IF.

Error Categories

Categorize errors for better management:

Category	Examples	Recovery Action
Data Errors	LENGERR, INVREQ	Validate input data
Resource Errors	NOTFND, FILEERR	Verify resource availability
System Errors	IOERR, COMMUNICATION FAIL	Escalate to operations
Ab-end Errors	Program checkout errors	Emergency procedures

Advanced Error Management

Condition Propagation

Handle condition propagation across program invocations:

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CONDITION-PROPAGATION-PATTERN.
    * Establish condition handlers
    EXEC CICS HANDLE CONDITION
        LENGERR(ERROR-LENGTH-PROPAGATION)
        INVREQ(ERROR-PROPAGATE-INVALID-REQUEST)
        FILEERR(ERROR-PROPAGATE-FILE-ERROR)
        TIMEDOUT(PG01AA)
    END-EXEC.
    
PROGRAM-RETURN.
    EVALUATE WS-RESPONSE
        WHEN DFHRESP(NORMAL)
            PERFORM NORMAL-RETURN-PROCESSING
       WHEN DFHRESP(LENGERR)
           PERFORM LENGERR-HANDLER
       WHEN DFHRESP(INVREQ)
           PERFORM INVREQ-HANDLER
       WHEN DFHRESP(FILEERR)
           PERFORM FILEERR-HANDLER
       WHEN DFHRESP(TIMEDOUT)
           PERFORM TIMEOUT-HANDLER
    END-EVALUATE.
    
    EXEC CICS RETURN TRANSID(WS-RETURN-TRANSID)
        COMMAREA(WS-ERROR-RESPONSE)
    END-EXEC.
    
ERROR-LENGTH-PROPAGATION.
    PERFORM HANDLE-LENGERR-FAILURE
    
ERROR-PROPAGATE-INVALID-REQUEST.
    PERFORM HANDLE-INVREQ-FAILURE
    
ERROR-PROPAGATE-FILE-ERROR.
    PERFORM HANDLE-FILEERR-FAILURE
    
PG01AA.
    PERFORM HANDLE-TIMEDOUT-FAILURE
    EXEC CICS RETURN END-EXEC.

Dynamic Error Handling

Implement dynamic error handling based on runtime conditions:

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DYNAMIC-ERROR-HANDLING.
    * Determine error handling strategy based on environment
    PERFORM CHECK-RUN-ENVIRONMENT
    
    EVALUATE WS-RUN-ENVIRONMENT
        WHEN 'PRODUCTION'
            PERFORM SET-PRODUCTION-ERROR-HANDLERS
        WHEN 'TEST'
            PERFORM SET-TEST-ERROR-HANDLERS
        WHEN 'DEVELOPMENT'
            PERFORM SET-DEVELOPMENT-ERROR-HANDLERS
    END-EVALUATE.
    
SET-PRODUCTION-ERROR-HANDLERS.
    EXEC CICS HANDLE CONDITION
        INVREQ(PRODUCTION-INVALID-REQUEST)
        FILEERR(PRODUCTION-FILE-ERROR)
        ABEND(PRODUCTION-ABEND-EXIT)
    END-EXEC.
 
SET-TEST-ERROR-HANDLERS.
    EXEC CICS HANDLE CONDITION
        INVREQ(TEST-INVALID-REQUEST)
        FILEERR(TEST-FILE-ERROR)
        ALL(DUMP-AND-RETURN)
    END-EXEC.
 
VERIFY-ERROR-HANDLER-UPDATES.
    PERFORM CHECK-CIRCUIT-COGNITUS-CHECK
    PERFORM VERIFY-INCOMING-CIRCUIT-RESULTS
    PERFORM CHECK-SYSTEM-COUNT-VALIDITY.
    
CHECK-SESSION-TICKET-TYPE.
    IF WS-TICKET-TYPE = 'ABEND'
        MOVE SPACE TO WS-SEVERITY-TYPE
        COMPUTE WS-SEVERITY-VALUE = ZERO
    END-IF.
    
CHECK-SYSTEM-COUNT-VALIDITY.
    PERFORM VERIFY-INCOMING-CIRCUIT-CHECK-RESULTS
    IF WS-RESTART-TICKET-RECOVERY-PARAMETER = 'Y'
        PERFORM RESTART-SESSION-RECOVERY
    END-IF.
 
VERIFY-INCOMING-CIRCUIT-CHECK-RESULTS.
    IF WS-RESTART-TICKET-RECOVERY-PARAMETER = 'Y'
        PERFORM RESTART-SESSION-RECOVERY
    END-IF.

Error Prevention

Input Validation

Prevent errors through robust input validation:

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INPUT-VALIDATION-PATTERN.
    PERFORM VALIDATE-INPUT-DATA-FORMAT
    PERFORM VALIDATE-INPUT-DATA-BOUNDS
    PERFORM VALIDATE-BUSINESS-RULES
    
    IF WS-VALIDATION-SUCCESSFUL = 'N'
        PERFORM DISPLAY-VALIDATION-ERRORS
        PERFORM REQUEST-CORRECTED-INPUT
        GO TO INPUT-VALIDATION-PATTERN
    END-IF.
 
VALIDATE-INPUT-DATA-FORMAT.
    * Check numeric fields
    INSPECT WS-INPUT-FIELD REPLACING ALL SPACES BY '0'
    
    * Validate date format
    IF WS-DATE-FIELD NOT NUMERIC
        SET WS-VALIDATION-ERROR TO TRUE
        DISPLAY 'ERROR: Invalid date format'
    END-IF.
    
    * Check field lengths
    IF LENGTH OF WS-CUSTOMER-ID NOT = EXPECTED-LENGTH
        SET WS-VALIDATION-ERROR TO TRUE
        DISPLAY 'ERROR: Customer ID length invalid'
    END-IF.

Resource Verification

Verify resources before using them:

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RESOURCE-VERIFICATION-PATTERN.
    * Check file availability
    EXEC CICS INQUIRE PROGRAM('FILE-CHECKER')
        STATUS(STARTED)
        RESP(WS-RESPONSE)
    END-EXEC.
    
    IF WS-RESPONSE NOT = DFHRESP(NORMAL)
        PERFORM HANDLE-FILE-UNAVAILABLE
    END-IF.
    
    * Check terminal status
    EXEC CICS EXTRACT ATTRIBUTES TERMID(WS-TERMINAL-ID)
        RESP(WS-RESPONSE)
    END-EXEC.
    
    IF WS-RESPONSE NOT = DFHRESP(NORMAL)
        PERFORM HANDLE-TERMINAL-UNAVAILABLE
    END-IF.

Best Practices Summary

Error Handling Checklist

Always check RESP and RESP2 codes
Implement appropriate condition handlers
Log errors with sufficient detail
Provide meaningful error messages to users
Have different error strategies for different environments
Test error conditions thoroughly
Document error recovery procedures
Monitor error trends and patterns

Common Mistakes to Avoid

Not checking response codes
Ignoring ab-end conditions
Using single error handler for all conditions
Not cleaning up after errors
Exposing internal errors to end users
Not testing error conditions

CICS Error Handling Management

Understanding CICS Response Codes

Response Code Structure

Common Response Codes

Condition Handlers

HANDLE CONDITION

HANDLE ABEND

Error Recovery Strategies

Immediate Recovery

Retry Logic

Error Logging and Monitoring

Centralized Error Logging

Error Categories

Advanced Error Management

Condition Propagation

Dynamic Error Handling

Error Prevention

Input Validation

Resource Verification

Best Practices Summary

Error Handling Checklist

Common Mistakes to Avoid

CICS Error Handling

CICS Program Logic

HANDLE CONDITION Command

RESET Command