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CICS INVOKE APPLICATION - Application Invocation

CICS INVOKE APPLICATION provides application invocation capabilities for programs and transactions. It enables programs to invoke applications, manage application execution, and handle application processing in CICS environments.

What is CICS INVOKE APPLICATION?

CICS INVOKE APPLICATION is a command that allows programs to invoke applications in the system. It provides application invocation capabilities, application execution management, and application processing for CICS applications.

Command Syntax

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EXEC CICS INVOKE APPLICATION
    APPLICATION(application-name)
    [PARAMETER(parameter-data)]
    [LENGTH(parameter-length)]
    [RESP(response-code)]
END-EXEC

Parameters

Required Parameters

  • APPLICATION(application-name) - Name of application to invoke

Optional Parameters

  • PARAMETER(parameter-data) - Parameter data for application
  • LENGTH(parameter-length) - Length of parameter data
  • RESP(response-code) - Response code variable

Application Types

Business Applications

Business application types

  • • ORDER PROCESSING - Order processing applications
  • • INVENTORY MANAGEMENT - Inventory management applications
  • • CUSTOMER MANAGEMENT - Customer management applications
  • • FINANCIAL PROCESSING - Financial processing applications

System Applications

System application types

  • • SYSTEM UTILITIES - System utility applications
  • • MONITORING APPLICATIONS - Monitoring applications
  • • REPORTING APPLICATIONS - Reporting applications
  • • MAINTENANCE APPLICATIONS - Maintenance applications

Communication Applications

Communication application types

  • • MESSAGE PROCESSING - Message processing applications
  • • DATA EXCHANGE - Data exchange applications
  • • INTERFACE APPLICATIONS - Interface applications
  • • INTEGRATION APPLICATIONS - Integration applications

Processing Applications

Processing application types

  • • BATCH PROCESSING - Batch processing applications
  • • REAL-TIME PROCESSING - Real-time processing applications
  • • DATA PROCESSING - Data processing applications
  • • TRANSACTION PROCESSING - Transaction processing applications

Programming Examples

Basic Application Invocation

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. INVAPP01.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  APPLICATION-NAME PIC X(8) VALUE 'ORDERAPP'.
       01  PARAMETER-DATA PIC X(100) VALUE 'ORDER123'.
       01  PARAMETER-LENGTH PIC S9(4) COMP VALUE 7.
       01  RESPONSE-CODE PIC S9(8) COMP.
       
       PROCEDURE DIVISION.
           DISPLAY 'Invoking application'
           DISPLAY 'Application: ' APPLICATION-NAME
           DISPLAY 'Parameter: ' PARAMETER-DATA
           
           EXEC CICS INVOKE APPLICATION
               APPLICATION(APPLICATION-NAME)
               PARAMETER(PARAMETER-DATA)
               LENGTH(PARAMETER-LENGTH)
               RESP(RESPONSE-CODE)
           END-EXEC
           
           IF RESPONSE-CODE = DFHRESP(NORMAL)
               DISPLAY 'Application invoked successfully'
           ELSE
               DISPLAY 'Application invocation failed'
           END-IF
           
           EXEC CICS RETURN END-EXEC.

Advanced Application Management

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. INVAPP02.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  APPLICATION-NAME PIC X(8).
       01  PARAMETER-DATA PIC X(100).
       01  PARAMETER-LENGTH PIC S9(4) COMP VALUE 100.
       01  RESPONSE-CODE PIC S9(8) COMP.
       01  INVOKE-COUNT PIC S9(2) COMP VALUE 0.
       01  MAX-INVOKES PIC S9(2) COMP VALUE 3.
       01  APP-STATUS PIC X(1).
       01  APPLICATION-LIST.
           05  APP-ITEM OCCURS 3 TIMES.
               10  APP-ID PIC X(8).
               10  APP-TYPE PIC X(8).
               10  APP-PARAMETER PIC X(50).
               10  APP-STATUS PIC X(1).
       
       PROCEDURE DIVISION.
           PERFORM INITIALIZE-APPLICATIONS
           PERFORM INVOKE-MULTIPLE-APPLICATIONS
           
           EXEC CICS RETURN END-EXEC.
       
       INITIALIZE-APPLICATIONS.
           MOVE 'ORDERAPP' TO APP-ID(1)
           MOVE 'BUSINESS' TO APP-TYPE(1)
           MOVE 'ORDER123' TO APP-PARAMETER(1)
           MOVE 'INVENTORY' TO APP-ID(2)
           MOVE 'BUSINESS' TO APP-TYPE(2)
           MOVE 'INV001' TO APP-PARAMETER(2)
           MOVE 'REPORTAPP' TO APP-ID(3)
           MOVE 'SYSTEM' TO APP-TYPE(3)
           MOVE 'RPT001' TO APP-PARAMETER(3).
       
       INVOKE-MULTIPLE-APPLICATIONS.
           PERFORM VARYING INVOKE-COUNT FROM 1 BY 1
               UNTIL INVOKE-COUNT > MAX-INVOKES
               
               MOVE APP-ID(INVOKE-COUNT) TO APPLICATION-NAME
               MOVE APP-PARAMETER(INVOKE-COUNT) TO PARAMETER-DATA
               MOVE 50 TO PARAMETER-LENGTH
               PERFORM INVOKE-SINGLE-APPLICATION
               
               IF RESPONSE-CODE = DFHRESP(NORMAL)
                   MOVE 'I' TO APP-STATUS(INVOKE-COUNT)
                   DISPLAY 'Application ' INVOKE-COUNT ' invoked successfully'
               ELSE
                   MOVE 'F' TO APP-STATUS(INVOKE-COUNT)
                   DISPLAY 'Application ' INVOKE-COUNT ' invocation failed'
               END-IF
           END-PERFORM.
       
       INVOKE-SINGLE-APPLICATION.
           EXEC CICS INVOKE APPLICATION
               APPLICATION(APPLICATION-NAME)
               PARAMETER(PARAMETER-DATA)
               LENGTH(PARAMETER-LENGTH)
               RESP(RESPONSE-CODE)
           END-EXEC.

Error Handling with Application Invocation

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. INVAPP03.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  APPLICATION-NAME PIC X(8) VALUE 'ORDERAPP'.
       01  PARAMETER-DATA PIC X(100) VALUE 'ORDER123'.
       01  PARAMETER-LENGTH PIC S9(4) COMP VALUE 7.
       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  APP-INVOKE-SUCCESSFUL PIC X(1) VALUE 'N'.
       
       PROCEDURE DIVISION.
           PERFORM INVOKE-APPLICATION-WITH-RETRY
           
           EXEC CICS RETURN END-EXEC.
       
       INVOKE-APPLICATION-WITH-RETRY.
           PERFORM INVOKE-APPLICATION
           
           IF RESPONSE-CODE NOT = DFHRESP(NORMAL)
               AND RETRY-COUNT < MAX-RETRIES
               ADD 1 TO RETRY-COUNT
               DISPLAY 'Retry ' RETRY-COUNT ' application invocation'
               PERFORM INVOKE-APPLICATION-WITH-RETRY
           END-IF.
       
       INVOKE-APPLICATION.
           EXEC CICS INVOKE APPLICATION
               APPLICATION(APPLICATION-NAME)
               PARAMETER(PARAMETER-DATA)
               LENGTH(PARAMETER-LENGTH)
               RESP(RESPONSE-CODE)
           END-EXEC
           
           EVALUATE RESPONSE-CODE
               WHEN DFHRESP(NORMAL)
                   MOVE 'Y' TO APP-INVOKE-SUCCESSFUL
                   DISPLAY 'Application invocation successful'
               WHEN DFHRESP(NOTAUTH)
                   DISPLAY 'Not authorized to invoke application'
               WHEN DFHRESP(INVREQ)
                   DISPLAY 'Invalid application invocation request'
               WHEN DFHRESP(APPERR)
                   DISPLAY 'Application invocation error'
               WHEN DFHRESP(APPNOTFOUND)
                   DISPLAY 'Application not found'
               WHEN DFHRESP(APPINUSE)
                   DISPLAY 'Application is in use'
               WHEN OTHER
                   DISPLAY 'Unexpected application invocation error'
           END-EVALUATE.

Application Management

Application Invocation

  • • Application Invoke - Invoke applications
  • • Application Execution - Execute applications
  • • Application Validation - Validate application state
  • • Application Monitoring - Monitor application status

Application Lifecycle

  • • Application Registration - Register applications
  • • Application Invocation - Invoke applications
  • • Application Execution - Execute applications
  • • Application Cleanup - Clean up applications

Application Monitoring

  • • Application Tracking - Track application usage
  • • Application Auditing - Audit application operations
  • • Application Reporting - Report application status
  • • Application Analysis - Analyze application patterns

Application Error Recovery

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

Error Handling

Common Response Codes

  • DFHRESP(NORMAL) - Application invocation successful
  • DFHRESP(NOTAUTH) - Not authorized to invoke application
  • DFHRESP(INVREQ) - Invalid application invocation request
  • DFHRESP(APPERR) - Application invocation error
  • DFHRESP(APPNOTFOUND) - Application not found
  • DFHRESP(APPINUSE) - Application is in use

Performance Considerations

Application Efficiency

  • • Optimize application operations - Use efficient application handling
  • • Minimize application overhead - Reduce application processing overhead
  • • Use application pooling - Implement application pooling
  • • Monitor application frequency - Track application invocation patterns

System Impact

  • • Monitor system impact - Track how application invocation affects the system
  • • Optimize application handling - Ensure efficient application processing
  • • Manage application usage - Monitor application consumption
  • • Track performance metrics - Monitor application handling performance

Best Practices

Application Invocation Best Practices

  • • Invoke applications only when needed
  • • Implement proper error handling for application operations
  • • Validate application state before invoking
  • • Use appropriate application management techniques
  • • Monitor application invocation activities and performance
  • • Maintain application invocation audit trails
  • • Handle application invocation errors gracefully

Explain It Like I'm 5 Years Old

Think of CICS INVOKE APPLICATION like calling a helper:

  • • Need Help: "You need help with something" - Need to invoke application
  • • Call Helper: "Call your helper to help you" - Invoke application
  • • Helper Comes: "Your helper comes to help" - Application invoked
  • • Get Help: "Get help from your helper" - Application executes
  • • Finish Task: "Finish your task with help" - Application completes

Exercises

Exercise 1: Basic Application Invocation

Create a program that invokes a basic application.

Exercise 2: Advanced Application Management

Write a program that manages multiple application invocations.

Exercise 3: Error Handling

Implement comprehensive error handling for application invocation failures.

Related Concepts

Application Management

Managing system applications

Application Invocation

Invoking applications

Application Execution

Executing applications

Application Monitoring

Monitoring applications

Error Handling

Managing application errors