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CICS GDS WAIT - GDS Event Synchronization

CICS GDS WAIT provides GDS event synchronization capabilities for programs and transactions. It enables programs to wait for GDS events, handle GDS event processing, and manage GDS event synchronization in CICS environments.

What is CICS GDS WAIT?

CICS GDS WAIT is a command that allows programs to wait for GDS events in the system. It provides GDS event synchronization capabilities, GDS event handling, and GDS event processing for CICS applications.

Command Syntax

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EXEC CICS GDS WAIT
    [EVENT(event-name)]
    [TIMEOUT(timeout-value)]
    [RESP(response-code)]
END-EXEC

Parameters

Optional Parameters

  • EVENT(event-name) - Name of GDS event to wait for
  • TIMEOUT(timeout-value) - Timeout value in seconds
  • RESP(response-code) - Response code variable

GDS Event Types

GDS Process Events

GDS process event types

  • • GDS PROCESS START - GDS process start events
  • • GDS PROCESS END - GDS process end events
  • • GDS PROCESS ERROR - GDS process error events
  • • GDS PROCESS STATUS - GDS process status events

GDS Communication Events

GDS communication event types

  • • GDS CONVERSATION START - GDS conversation start events
  • • GDS CONVERSATION END - GDS conversation end events
  • • GDS SESSION START - GDS session start events
  • • GDS SESSION END - GDS session end events

GDS Data Events

GDS data event types

  • • GDS DATA RECEIVED - GDS data received events
  • • GDS DATA SENT - GDS data sent events
  • • GDS MESSAGE RECEIVED - GDS message received events
  • • GDS MESSAGE SENT - GDS message sent events

GDS System Events

GDS system event types

  • • GDS SYSTEM START - GDS system start events
  • • GDS SYSTEM END - GDS system end events
  • • GDS SYSTEM ERROR - GDS system error events
  • • GDS SYSTEM STATUS - GDS system status events

Programming Examples

Basic GDS Event Synchronization

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. GDSWAIT01.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  EVENT-NAME PIC X(8) VALUE 'GDSEVT01'.
       01  TIMEOUT-VALUE PIC S9(4) COMP VALUE 30.
       01  RESPONSE-CODE PIC S9(8) COMP.
       
       PROCEDURE DIVISION.
           DISPLAY 'Waiting for GDS event'
           DISPLAY 'Event: ' EVENT-NAME
           DISPLAY 'Timeout: ' TIMEOUT-VALUE ' seconds'
           
           EXEC CICS GDS WAIT
               EVENT(EVENT-NAME)
               TIMEOUT(TIMEOUT-VALUE)
               RESP(RESPONSE-CODE)
           END-EXEC
           
           IF RESPONSE-CODE = DFHRESP(NORMAL)
               DISPLAY 'GDS event received successfully'
           ELSE
               DISPLAY 'GDS event wait failed or timed out'
           END-IF
           
           EXEC CICS RETURN END-EXEC.

Advanced GDS Event Handling

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. GDSWAIT02.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  EVENT-NAME PIC X(8).
       01  TIMEOUT-VALUE PIC S9(4) COMP VALUE 30.
       01  RESPONSE-CODE PIC S9(8) COMP.
       01  WAIT-COUNT PIC S9(2) COMP VALUE 0.
       01  MAX-WAITS PIC S9(2) COMP VALUE 3.
       01  GDS-STATUS PIC X(1).
       01  EVENT-LIST.
           05  EVENT-ITEM OCCURS 3 TIMES.
               10  EVENT-ID PIC X(8).
               10  EVENT-TYPE PIC X(8).
               10  EVENT-STATUS PIC X(1).
       
       PROCEDURE DIVISION.
           PERFORM INITIALIZE-GDS-EVENTS
           PERFORM WAIT-MULTIPLE-GDS-EVENTS
           
           EXEC CICS RETURN END-EXEC.
       
       INITIALIZE-GDS-EVENTS.
           MOVE 'GDSEVT01' TO EVENT-ID(1)
           MOVE 'PROCESS' TO EVENT-TYPE(1)
           MOVE 'GDSEVT02' TO EVENT-ID(2)
           MOVE 'COMMUNICATION' TO EVENT-TYPE(2)
           MOVE 'GDSEVT03' TO EVENT-ID(3)
           MOVE 'DATA' TO EVENT-TYPE(3).
       
       WAIT-MULTIPLE-GDS-EVENTS.
           PERFORM VARYING WAIT-COUNT FROM 1 BY 1
               UNTIL WAIT-COUNT > MAX-WAITS
               
               MOVE EVENT-ID(WAIT-COUNT) TO EVENT-NAME
               PERFORM WAIT-SINGLE-GDS-EVENT
               
               IF RESPONSE-CODE = DFHRESP(NORMAL)
                   MOVE 'W' TO EVENT-STATUS(WAIT-COUNT)
                   DISPLAY 'GDS event ' WAIT-COUNT ' received successfully'
               ELSE
                   MOVE 'F' TO EVENT-STATUS(WAIT-COUNT)
                   DISPLAY 'GDS event ' WAIT-COUNT ' wait failed or timed out'
               END-IF
           END-PERFORM.
       
       WAIT-SINGLE-GDS-EVENT.
           EXEC CICS GDS WAIT
               EVENT(EVENT-NAME)
               TIMEOUT(TIMEOUT-VALUE)
               RESP(RESPONSE-CODE)
           END-EXEC.

Error Handling with GDS Event Synchronization

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. GDSWAIT03.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  EVENT-NAME PIC X(8) VALUE 'GDSEVT01'.
       01  TIMEOUT-VALUE PIC S9(4) COMP VALUE 30.
       01  RESPONSE-CODE PIC S9(8) COMP.
       01  RETRY-COUNT PIC S9(2) COMP VALUE 0.
       01  MAX-RETRIES PIC S9(2) COMP VALUE 3.
       01  GDS-WAIT-SUCCESSFUL PIC X(1) VALUE 'N'.
       
       PROCEDURE DIVISION.
           PERFORM WAIT-GDS-EVENT-WITH-RETRY
           
           EXEC CICS RETURN END-EXEC.
       
       WAIT-GDS-EVENT-WITH-RETRY.
           PERFORM WAIT-GDS-EVENT
           
           IF RESPONSE-CODE NOT = DFHRESP(NORMAL)
               AND RETRY-COUNT < MAX-RETRIES
               ADD 1 TO RETRY-COUNT
               DISPLAY 'Retry ' RETRY-COUNT ' GDS event wait operation'
               PERFORM WAIT-GDS-EVENT-WITH-RETRY
           END-IF.
       
       WAIT-GDS-EVENT.
           EXEC CICS GDS WAIT
               EVENT(EVENT-NAME)
               TIMEOUT(TIMEOUT-VALUE)
               RESP(RESPONSE-CODE)
           END-EXEC
           
           EVALUATE RESPONSE-CODE
               WHEN DFHRESP(NORMAL)
                   MOVE 'Y' TO GDS-WAIT-SUCCESSFUL
                   DISPLAY 'GDS event wait operation successful'
               WHEN DFHRESP(NOTAUTH)
                   DISPLAY 'Not authorized to wait for GDS event'
               WHEN DFHRESP(INVREQ)
                   DISPLAY 'Invalid GDS event wait request'
               WHEN DFHRESP(WAITERR)
                   DISPLAY 'GDS event wait operation error'
               WHEN DFHRESP(TIMEOUT)
                   DISPLAY 'GDS event wait timed out'
               WHEN DFHRESP(EVENTNOTFOUND)
                   DISPLAY 'GDS event not found'
               WHEN OTHER
                   DISPLAY 'Unexpected GDS event wait error'
           END-EVALUATE.

GDS Event Processing

GDS Event Synchronization

  • • GDS Event Wait - Wait for GDS events
  • • GDS Event Handling - Handle GDS events
  • • GDS Event Processing - Process GDS events
  • • GDS Event Monitoring - Monitor GDS events

GDS Event Lifecycle

  • • GDS Event Creation - Create GDS events
  • • GDS Event Waiting - Wait for GDS events
  • • GDS Event Processing - Process GDS events
  • • GDS Event Cleanup - Clean up GDS events

GDS Event Monitoring

  • • GDS Event Tracking - Track GDS event flow
  • • GDS Event Auditing - Audit GDS event operations
  • • GDS Event Reporting - Report GDS event status
  • • GDS Event Analysis - Analyze GDS event patterns

GDS Error Recovery

  • • GDS Error Detection - Detect GDS event errors
  • • GDS Error Recovery - Recover from GDS event errors
  • • GDS Retry Mechanisms - Implement GDS retry logic
  • • GDS Fallback Procedures - Use GDS fallback procedures

Error Handling

Common Response Codes

  • DFHRESP(NORMAL) - GDS event wait operation successful
  • DFHRESP(NOTAUTH) - Not authorized to wait for GDS event
  • DFHRESP(INVREQ) - Invalid GDS event wait request
  • DFHRESP(WAITERR) - GDS event wait operation error
  • DFHRESP(TIMEOUT) - GDS event wait timed out
  • DFHRESP(EVENTNOTFOUND) - GDS event not found

Performance Considerations

GDS Event Efficiency

  • • Optimize GDS event operations - Use efficient GDS event handling
  • • Minimize GDS event overhead - Reduce GDS event processing overhead
  • • Use GDS event pooling - Implement GDS event pooling
  • • Monitor GDS event frequency - Track GDS event wait patterns

System Impact

  • • Monitor system impact - Track how GDS event wait affects the system
  • • Optimize GDS event handling - Ensure efficient GDS event processing
  • • Manage GDS event usage - Monitor GDS event consumption
  • • Track performance metrics - Monitor GDS event handling performance

Best Practices

GDS Event Synchronization Best Practices

  • • Wait for GDS events only when needed
  • • Implement proper error handling for GDS event operations
  • • Set appropriate timeout values for GDS event waits
  • • Use appropriate GDS event management techniques
  • • Monitor GDS event synchronization activities and performance
  • • Maintain GDS event synchronization audit trails
  • • Handle GDS event synchronization errors gracefully

Explain It Like I'm 5 Years Old

Think of CICS GDS WAIT like waiting for your friend:

  • • Want to Play: "You want to play with your friend" - Need to wait for GDS event
  • • Wait for Friend: "Wait for your friend to come" - Wait for GDS event
  • • Friend Arrives: "Your friend arrives" - GDS event received
  • • Start Playing: "Start playing with your friend" - Process GDS event
  • • Keep Playing: "Keep playing until done" - Continue GDS event processing

Exercises

Exercise 1: Basic GDS Event Synchronization

Create a program that waits for a basic GDS event.

Exercise 2: Advanced GDS Event Handling

Write a program that manages multiple GDS event synchronizations.

Exercise 3: Error Handling

Implement comprehensive error handling for GDS event synchronization failures.

Related Concepts

GDS Event Processing

Processing GDS system events

GDS Event Synchronization

Synchronizing GDS events

GDS Event Handling

Handling GDS events

GDS Event Monitoring

Monitoring GDS events

Error Handling

Managing GDS event errors