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CICS ACQUIRE - Resource Acquisition

CICS ACQUIRE provides resource acquisition capabilities for programs and transactions. It enables programs to acquire resources, manage resource allocation, and handle resource acquisition operations in CICS environments.

What is CICS ACQUIRE?

CICS ACQUIRE is a command that allows programs to acquire resources such as files, databases, queues, and other system resources. It provides resource management capabilities, resource allocation control, and resource acquisition operations for CICS applications.

Command Syntax

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

Parameters

Required Parameters

  • RESOURCE(resource-name) - Name of resource to acquire

Optional Parameters

  • RESP(response-code) - Response code variable

Resource Types

File Resources

File system resources

  • • VSAM FILES - Acquire VSAM file resources
  • • QSAM FILES - Acquire QSAM file resources
  • • BDAM FILES - Acquire BDAM file resources
  • • FILE POOLS - Acquire file pool resources

Database Resources

Database system resources

  • • DB2 CONNECTIONS - Acquire DB2 connection resources
  • • IMS CONNECTIONS - Acquire IMS connection resources
  • • DATABASE POOLS - Acquire database pool resources
  • • CONNECTION POOLS - Acquire connection pool resources

Queue Resources

Queue system resources

  • • TS QUEUES - Acquire TS queue resources
  • • TD QUEUES - Acquire TD queue resources
  • • QUEUE POOLS - Acquire queue pool resources
  • • MESSAGE QUEUES - Acquire message queue resources

System Resources

System-level resources

  • • MEMORY POOLS - Acquire memory pool resources
  • • PROCESSOR POOLS - Acquire processor pool resources
  • • STORAGE POOLS - Acquire storage pool resources
  • • NETWORK RESOURCES - Acquire network resources

Programming Examples

Basic Resource Acquisition

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. ACQUIRE01.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  RESOURCE-NAME PIC X(8) VALUE 'MYFILE01'.
       01  RESPONSE-CODE PIC S9(8) COMP.
       01  RESOURCE-ACQUIRED PIC X(1) VALUE 'N'.
       
       PROCEDURE DIVISION.
           IF RESOURCE-ACQUIRED = 'N'
               DISPLAY 'Acquiring resource: ' RESOURCE-NAME
               
               EXEC CICS ACQUIRE
                   RESOURCE(RESOURCE-NAME)
                   RESP(RESPONSE-CODE)
               END-EXEC
               
               IF RESPONSE-CODE = DFHRESP(NORMAL)
                   MOVE 'Y' TO RESOURCE-ACQUIRED
                   DISPLAY 'Resource acquired successfully'
               ELSE
                   DISPLAY 'Failed to acquire resource'
               END-IF
           ELSE
               DISPLAY 'Resource already acquired'
           END-IF
           
           EXEC CICS RETURN END-EXEC.

Advanced Resource Management

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. ACQUIRE02.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  RESOURCE-NAME PIC X(8).
       01  RESPONSE-CODE PIC S9(8) COMP.
       01  RESOURCE-COUNT PIC S9(2) COMP VALUE 0.
       01  MAX-RESOURCES PIC S9(2) COMP VALUE 5.
       01  RESOURCE-LIST.
           05  RESOURCE-ITEM OCCURS 5 TIMES.
               10  RESOURCE-ID PIC X(8).
               10  RESOURCE-STATUS PIC X(1).
       
       PROCEDURE DIVISION.
           PERFORM ACQUIRE-MULTIPLE-RESOURCES
           
           EXEC CICS RETURN END-EXEC.
       
       ACQUIRE-MULTIPLE-RESOURCES.
           MOVE 'FILE001' TO RESOURCE-ID(1)
           MOVE 'FILE002' TO RESOURCE-ID(2)
           MOVE 'QUEUE01' TO RESOURCE-ID(3)
           MOVE 'DB2CONN' TO RESOURCE-ID(4)
           MOVE 'MEMORY01' TO RESOURCE-ID(5)
           
           PERFORM VARYING RESOURCE-COUNT FROM 1 BY 1
               UNTIL RESOURCE-COUNT > MAX-RESOURCES
               
               MOVE RESOURCE-ID(RESOURCE-COUNT) TO RESOURCE-NAME
               PERFORM ACQUIRE-SINGLE-RESOURCE
               
               IF RESPONSE-CODE = DFHRESP(NORMAL)
                   MOVE 'A' TO RESOURCE-STATUS(RESOURCE-COUNT)
                   DISPLAY 'Acquired: ' RESOURCE-NAME
               ELSE
                   MOVE 'F' TO RESOURCE-STATUS(RESOURCE-COUNT)
                   DISPLAY 'Failed: ' RESOURCE-NAME
               END-IF
           END-PERFORM.
       
       ACQUIRE-SINGLE-RESOURCE.
           EXEC CICS ACQUIRE
               RESOURCE(RESOURCE-NAME)
               RESP(RESPONSE-CODE)
           END-EXEC.

Error Handling with Resource Acquisition

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. ACQUIRE03.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  RESOURCE-NAME PIC X(8) VALUE 'TESTFILE'.
       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  ACQUISITION-SUCCESSFUL PIC X(1) VALUE 'N'.
       
       PROCEDURE DIVISION.
           PERFORM ACQUIRE-WITH-ERROR-HANDLING
           
           EXEC CICS RETURN END-EXEC.
       
       ACQUIRE-WITH-ERROR-HANDLING.
           PERFORM ACQUIRE-RESOURCE
           
           IF RESPONSE-CODE NOT = DFHRESP(NORMAL)
               AND RETRY-COUNT < MAX-RETRIES
               ADD 1 TO RETRY-COUNT
               DISPLAY 'Retry ' RETRY-COUNT ' acquiring resource'
               PERFORM ACQUIRE-WITH-ERROR-HANDLING
           END-IF.
       
       ACQUIRE-RESOURCE.
           EXEC CICS ACQUIRE
               RESOURCE(RESOURCE-NAME)
               RESP(RESPONSE-CODE)
           END-EXEC
           
           EVALUATE RESPONSE-CODE
               WHEN DFHRESP(NORMAL)
                   MOVE 'Y' TO ACQUISITION-SUCCESSFUL
                   DISPLAY 'Resource acquired successfully'
               WHEN DFHRESP(NOTFND)
                   DISPLAY 'Resource not found'
               WHEN DFHRESP(NOTAUTH)
                   DISPLAY 'Not authorized to acquire resource'
               WHEN DFHRESP(INVREQ)
                   DISPLAY 'Invalid resource request'
               WHEN DFHRESP(RESOURCEERR)
                   DISPLAY 'Resource acquisition error'
               WHEN OTHER
                   DISPLAY 'Unexpected error occurred'
           END-EVALUATE.

Resource Management

Resource Allocation

  • • Resource Pooling - Manage resource pools
  • • Resource Sharing - Share resources between programs
  • • Resource Limits - Enforce resource limits
  • • Resource Quotas - Manage resource quotas

Resource Monitoring

  • • Resource Usage - Monitor resource usage
  • • Resource Availability - Check resource availability
  • • Resource Status - Track resource status
  • • Resource Health - Monitor resource health

Resource Lifecycle

  • • Resource Creation - Create new resources
  • • Resource Initialization - Initialize resources
  • • Resource Cleanup - Clean up resources
  • • Resource Destruction - Destroy resources

Error Recovery

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

Error Handling

Common Response Codes

  • DFHRESP(NORMAL) - Resource acquired successfully
  • DFHRESP(NOTFND) - Resource not found
  • DFHRESP(NOTAUTH) - Not authorized to acquire resource
  • DFHRESP(INVREQ) - Invalid resource request
  • DFHRESP(RESOURCEERR) - Resource acquisition error
  • DFHRESP(QUOTAERR) - Resource quota exceeded

Performance Considerations

Resource Efficiency

  • • Optimize resource usage - Use resources efficiently
  • • Minimize resource overhead - Reduce resource processing overhead
  • • Use resource pooling - Implement resource pooling
  • • Monitor resource frequency - Track resource acquisition patterns

System Impact

  • • Monitor system impact - Track how resources affect the system
  • • Optimize resource handling - Ensure efficient resource processing
  • • Manage resource usage - Monitor resource consumption
  • • Track performance metrics - Monitor resource handling performance

Best Practices

Resource Acquisition Best Practices

  • • Acquire resources only when needed
  • • Implement proper error handling for resource operations
  • • Release resources promptly after use
  • • Use resource pooling for better performance
  • • Monitor resource usage and availability
  • • Maintain resource audit trails
  • • Handle resource errors gracefully

Explain It Like I'm 5 Years Old

Think of CICS ACQUIRE like borrowing a toy:

  • • Ask for Toy: "Can I borrow your toy?" - Request resource
  • • Get Permission: "Yes, you can borrow it" - Acquire resource
  • • Use the Toy: "Play with the toy carefully" - Use resource
  • • Return Toy: "Give the toy back when done" - Release resource
  • • Share Toys: "Other kids can borrow it too" - Resource sharing

Exercises

Exercise 1: Basic Resource Acquisition

Create a program that acquires a file resource and handles the response.

Exercise 2: Advanced Resource Management

Write a program that acquires multiple resources and manages their lifecycle.

Exercise 3: Error Handling

Implement comprehensive error handling for resource acquisition failures.

Related Concepts

Resource Management

Managing system resources

File Operations

File system operations

Database Operations

Database system operations

Queue Operations

Queue system operations

Error Handling

Managing resource errors