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CICS WAIT EVENT - Event Waiting

CICS WAIT EVENT suspends the current task until a specific event occurs. It enables programs to wait for events, manage event operations, and handle event waiting in CICS applications.

What is CICS WAIT EVENT?

CICS WAIT EVENT is a command that allows programs to suspend the current task until a specific event occurs. It provides event waiting capabilities, task coordination, and event management for CICS applications.

Command Syntax

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EXEC CICS WAIT EVENT
    EVENT(event-name)
    [RESP(response-code)]
END-EXEC

Parameters

Required Parameters

  • EVENT(event-name) - Name of the event to wait for

Optional Parameters

  • RESP(response-code) - Response code variable

Programming Examples

Basic Event Waiting

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WORKING-STORAGE SECTION.
01  EVENT-NAME           PIC X(8) VALUE 'MYEVENT'.
01  RESPONSE-CODE        PIC S9(8) COMP.
 
PROCEDURE DIVISION.
    DISPLAY 'Waiting for event: ' EVENT-NAME
    
    *> Wait for the event to occur
    EXEC CICS WAIT EVENT
        EVENT(EVENT-NAME)
        RESP(RESPONSE-CODE)
    END-EXEC.
    
    IF RESPONSE-CODE = DFHRESP(NORMAL)
        DISPLAY 'Event received successfully'
        DISPLAY 'Continuing with processing...'
        
        *> Process the event
        PERFORM PROCESS-EVENT
    ELSE
        IF RESPONSE-CODE = DFHRESP(TIMEOUT)
            DISPLAY 'Timeout waiting for event'
        ELSE
            DISPLAY 'Error waiting for event: ' RESPONSE-CODE
        END-IF
    END-IF.
 
PROCESS-EVENT.
    DISPLAY 'Processing event: ' EVENT-NAME
    *> Add event processing logic here
    EXIT.

Error Handling

Common Response Codes

  • DFHRESP(NORMAL) - Event received successfully
  • DFHRESP(TIMEOUT) - Timeout waiting for event
  • DFHRESP(INVREQ) - Invalid request or parameter
  • DFHRESP(NOTAUTH) - Not authorized to wait for event

Performance Considerations

Efficiency

  • • Task Suspension - WAIT EVENT suspends the task, freeing CPU resources
  • • Timeout Management - Use appropriate timeout values to avoid indefinite waits
  • • Throughput Impact - Consider the impact on transaction throughput

Best Practices

  • • Error Handling - Always check the response code for error handling
  • • Event Naming - Use meaningful event names for easier management
  • • Coordination - Coordinate event signaling with event waiting

Explain It Like I'm 5 Years Old

Think of CICS WAIT EVENT like waiting for your friend to knock:

  • • Waiting by Door: "You sit by the door waiting for your friend" - WAIT EVENT
  • • Friend's Name: "You're waiting for your friend Sarah to knock" - Event name
  • • Knock Sound: "When you hear the knock, you know Sarah is here" - Event occurs
  • • Open Door: "You open the door and start playing" - Process event

Exercises

Exercise 1: Basic Event Waiting

Create a program that waits for an event and then processes it.

Exercise 2: Event Signaling

Write a program that signals an event for another task to wait for.

Exercise 3: Error Handling

Implement error handling for the WAIT EVENT command.

Related Concepts

Event Management

Managing events in CICS

SIGNAL EVENT

Signaling events

Task Coordination

Coordinating tasks

Synchronization

Synchronizing tasks

Error Handling

Handling event errors