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CICS GDS FREE - GDS Resource Deallocation

CICS GDS FREE provides GDS resource deallocation capabilities for programs and transactions. It enables programs to free GDS resources, manage GDS resource cleanup, and handle GDS resource deallocation in CICS environments.

What is CICS GDS FREE?

CICS GDS FREE is a command that allows programs to deallocate GDS resources in the system. It provides GDS resource deallocation capabilities, GDS resource cleanup, and GDS resource management for CICS applications.

Command Syntax

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EXEC CICS GDS FREE
    [RESOURCE(resource-name)]
    [RESP(response-code)]
END-EXEC

Parameters

Optional Parameters

  • RESOURCE(resource-name) - Name of GDS resource to free
  • RESP(response-code) - Response code variable

GDS Resource Types

GDS Memory Resources

GDS memory resource types

  • • GDS MAIN STORAGE - GDS main storage resources
  • • GDS AUXILIARY STORAGE - GDS auxiliary storage resources
  • • GDS VIRTUAL STORAGE - GDS virtual storage resources
  • • GDS SHARED STORAGE - GDS shared storage resources

GDS Process Resources

GDS process resource types

  • • GDS PROCESS - GDS process resources
  • • GDS THREAD - GDS thread resources
  • • GDS HANDLE - GDS handle resources
  • • GDS EVENT - GDS event resources

GDS Communication Resources

GDS communication resource types

  • • GDS CONVERSATION - GDS conversation resources
  • • GDS SESSION - GDS session resources
  • • GDS CONNECTION - GDS connection resources
  • • GDS CHANNEL - GDS channel resources

GDS Data Resources

GDS data resource types

  • • GDS DATA - GDS data resources
  • • GDS MESSAGE - GDS message resources
  • • GDS BUFFER - GDS buffer resources
  • • GDS QUEUE - GDS queue resources

Programming Examples

Basic GDS Resource Deallocation

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. GDSFREE01.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  RESOURCE-NAME PIC X(8) VALUE 'GDSMEM01'.
       01  RESPONSE-CODE PIC S9(8) COMP.
       
       PROCEDURE DIVISION.
           DISPLAY 'Freeing GDS resource'
           DISPLAY 'Resource: ' RESOURCE-NAME
           
           EXEC CICS GDS FREE
               RESOURCE(RESOURCE-NAME)
               RESP(RESPONSE-CODE)
           END-EXEC
           
           IF RESPONSE-CODE = DFHRESP(NORMAL)
               DISPLAY 'GDS resource freed successfully'
           ELSE
               DISPLAY 'GDS resource free failed'
           END-IF
           
           EXEC CICS RETURN END-EXEC.

Advanced GDS Resource Management

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. GDSFREE02.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  RESOURCE-NAME PIC X(8).
       01  RESPONSE-CODE PIC S9(8) COMP.
       01  FREE-COUNT PIC S9(2) COMP VALUE 0.
       01  MAX-FREES PIC S9(2) COMP VALUE 3.
       01  GDS-STATUS PIC X(1).
       01  RESOURCE-LIST.
           05  RESOURCE-ITEM OCCURS 3 TIMES.
               10  RESOURCE-ID PIC X(8).
               10  RESOURCE-TYPE PIC X(8).
               10  RESOURCE-STATUS PIC X(1).
       
       PROCEDURE DIVISION.
           PERFORM INITIALIZE-GDS-RESOURCES
           PERFORM FREE-MULTIPLE-GDS-RESOURCES
           
           EXEC CICS RETURN END-EXEC.
       
       INITIALIZE-GDS-RESOURCES.
           MOVE 'GDSMEM01' TO RESOURCE-ID(1)
           MOVE 'MEMORY' TO RESOURCE-TYPE(1)
           MOVE 'GDSPROC01' TO RESOURCE-ID(2)
           MOVE 'PROCESS' TO RESOURCE-TYPE(2)
           MOVE 'GDSCONV01' TO RESOURCE-ID(3)
           MOVE 'CONVERSATION' TO RESOURCE-TYPE(3).
       
       FREE-MULTIPLE-GDS-RESOURCES.
           PERFORM VARYING FREE-COUNT FROM 1 BY 1
               UNTIL FREE-COUNT > MAX-FREES
               
               MOVE RESOURCE-ID(FREE-COUNT) TO RESOURCE-NAME
               PERFORM FREE-SINGLE-GDS-RESOURCE
               
               IF RESPONSE-CODE = DFHRESP(NORMAL)
                   MOVE 'F' TO RESOURCE-STATUS(FREE-COUNT)
                   DISPLAY 'GDS resource ' FREE-COUNT ' freed successfully'
               ELSE
                   MOVE 'E' TO RESOURCE-STATUS(FREE-COUNT)
                   DISPLAY 'GDS resource ' FREE-COUNT ' free failed'
               END-IF
           END-PERFORM.
       
       FREE-SINGLE-GDS-RESOURCE.
           EXEC CICS GDS FREE
               RESOURCE(RESOURCE-NAME)
               RESP(RESPONSE-CODE)
           END-EXEC.

Error Handling with GDS Resource Deallocation

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. GDSFREE03.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  RESOURCE-NAME PIC X(8) VALUE 'GDSMEM01'.
       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-FREE-SUCCESSFUL PIC X(1) VALUE 'N'.
       
       PROCEDURE DIVISION.
           PERFORM FREE-GDS-RESOURCE-WITH-RETRY
           
           EXEC CICS RETURN END-EXEC.
       
       FREE-GDS-RESOURCE-WITH-RETRY.
           PERFORM FREE-GDS-RESOURCE
           
           IF RESPONSE-CODE NOT = DFHRESP(NORMAL)
               AND RETRY-COUNT < MAX-RETRIES
               ADD 1 TO RETRY-COUNT
               DISPLAY 'Retry ' RETRY-COUNT ' GDS resource free operation'
               PERFORM FREE-GDS-RESOURCE-WITH-RETRY
           END-IF.
       
       FREE-GDS-RESOURCE.
           EXEC CICS GDS FREE
               RESOURCE(RESOURCE-NAME)
               RESP(RESPONSE-CODE)
           END-EXEC
           
           EVALUATE RESPONSE-CODE
               WHEN DFHRESP(NORMAL)
                   MOVE 'Y' TO GDS-FREE-SUCCESSFUL
                   DISPLAY 'GDS resource free operation successful'
               WHEN DFHRESP(NOTAUTH)
                   DISPLAY 'Not authorized to free GDS resource'
               WHEN DFHRESP(INVREQ)
                   DISPLAY 'Invalid GDS resource free request'
               WHEN DFHRESP(RESOURCEERR)
                   DISPLAY 'GDS resource free operation error'
               WHEN DFHRESP(RESOURCENOTFOUND)
                   DISPLAY 'GDS resource not found'
               WHEN DFHRESP(RESOURCEINUSE)
                   DISPLAY 'GDS resource is in use'
               WHEN OTHER
                   DISPLAY 'Unexpected GDS resource free error'
           END-EVALUATE.

GDS Resource Management

GDS Resource Deallocation

  • • GDS Resource Free - Free allocated GDS resources
  • • GDS Resource Cleanup - Clean up GDS resource state
  • • GDS Resource Validation - Validate GDS resource state
  • • GDS Resource Monitoring - Monitor GDS resource status

GDS Resource Lifecycle

  • • GDS Resource Allocation - Allocate GDS resources
  • • GDS Resource Usage - Use allocated GDS resources
  • • GDS Resource Deallocation - Deallocate GDS resources
  • • GDS Resource Cleanup - Clean up GDS resources

GDS Resource Monitoring

  • • GDS Resource Tracking - Track GDS resource usage
  • • GDS Resource Auditing - Audit GDS resource operations
  • • GDS Resource Reporting - Report GDS resource status
  • • GDS Resource Analysis - Analyze GDS resource patterns

GDS Error Recovery

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

Error Handling

Common Response Codes

  • DFHRESP(NORMAL) - GDS resource free operation successful
  • DFHRESP(NOTAUTH) - Not authorized to free GDS resource
  • DFHRESP(INVREQ) - Invalid GDS resource free request
  • DFHRESP(RESOURCEERR) - GDS resource free operation error
  • DFHRESP(RESOURCENOTFOUND) - GDS resource not found
  • DFHRESP(RESOURCEINUSE) - GDS resource is in use

Performance Considerations

GDS Resource Efficiency

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

System Impact

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

Best Practices

GDS Resource Deallocation Best Practices

  • • Free GDS resources as soon as they are no longer needed
  • • Implement proper error handling for GDS resource operations
  • • Validate GDS resource state before freeing
  • • Use appropriate GDS resource management techniques
  • • Monitor GDS resource deallocation activities and performance
  • • Maintain GDS resource deallocation audit trails
  • • Handle GDS resource deallocation errors gracefully

Explain It Like I'm 5 Years Old

Think of CICS GDS FREE like putting away your GDS toys:

  • • Finished Playing: "You finished playing with your GDS toys" - GDS resource no longer needed
  • • Put Away: "Put your GDS toys away" - Free GDS resource
  • • Clean Up: "Clean up your GDS toy area" - GDS resource cleanup
  • • Room Clean: "Your GDS toy area is clean now" - GDS resource freed
  • • Keep Clean: "Keep your GDS toy area clean" - GDS resource management

Exercises

Exercise 1: Basic GDS Resource Deallocation

Create a program that frees a basic GDS resource.

Exercise 2: Advanced GDS Resource Management

Write a program that manages multiple GDS resource deallocations.

Exercise 3: Error Handling

Implement comprehensive error handling for GDS resource deallocation failures.

Related Concepts

GDS Resource Management

Managing GDS system resources

GDS Resource Deallocation

Deallocating GDS resources

GDS Resource Monitoring

Monitoring GDS resource usage

GDS Resource Cleanup

Cleaning up GDS resources

Error Handling

Managing GDS resource errors