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CICS MSG - Message

CICS MSG provides message management capabilities, enabling message processing and output processing in CICS environments. It provides efficient message capabilities for CICS applications.

What is CICS MSG?

CICS MSG provides message management capabilities, enabling message processing and output processing. It provides efficient message capabilities, allowing applications to manage message operations.

Command Syntax

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EXEC CICS MSG
    [RESP(response-code)]
    [RESP2(response-code-2)]
END-EXEC.

Parameters Explained

RESP Parameters

Response codes returned by the command:

  • RESP: Primary response code - indicates the success or failure of the message operation
  • RESP2: Secondary response code - provides additional error information when RESP indicates failure
  • Always check these codes for command success before proceeding with data processing
  • Handle command failures appropriately to prevent application errors

Message Types

1. Basic Messages

  • Basic messages: Standard message operations that handle simple messaging without special formatting
  • Mapped messages: Message operations that use predefined field mappings to structure message data
  • Unmapped messages: Raw message operations that handle unstructured messaging without predefined field mappings
  • Custom messages: Specialized message operations designed for specific application requirements

2. Advanced Messages

  • Advanced messages: Complex message operations that handle sophisticated messaging processing and validation
  • Secure messages: Message operations that include encryption and security features for sensitive messaging
  • Encrypted messages: Message operations that automatically encrypt message data
  • Compressed messages: Message operations that handle compressed messaging streams and automatically compress message data

3. Specialized Messages

  • Specialized messages: Message operations tailored for specific protocols or communication methods
  • High-performance messages: Optimized message operations designed for maximum throughput and efficiency
  • Low-latency messages: Message operations optimized for minimal delay and real-time processing requirements
  • High-throughput messages: Message operations designed to handle large volumes of messaging efficiently

Implementation Example

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WORKING-STORAGE SECTION.
01 WS-RESPONSE            PIC S9(8) COMP.
01 WS-RESPONSE2           PIC S9(8) COMP.
 
PROCEDURE DIVISION.
    * Message operation
    EXEC CICS MSG
        RESP(WS-RESPONSE)
        RESP2(WS-RESPONSE2)
    END-EXEC.
    
    IF WS-RESPONSE NOT EQUAL DFHRESP(NORMAL)
        EXEC CICS WRITE OPERATOR
            TEXT('MSG command failed')
        END-EXEC
        EXEC CICS RETURN END-EXEC
    END-IF.
    
    * Message operation completed successfully
    * Continue processing

Message Processing

1. Message Preparation

Message preparation includes:

  • Message validation - ensuring the message operation is properly configured and authorized
  • Message formatting - preparing data structures and buffers for message data
  • Message encoding - setting up proper character encoding and data transformation
  • Message processing - initializing the message operation and preparing for messaging

2. Message Transmission

Message transmission includes:

  • Message routing - directing message data to the appropriate processing location
  • Message delivery - ensuring message data reaches the correct destination within the application
  • Transmission confirmation - verifying that message was completed successfully
  • Error handling - managing transmission failures and implementing retry mechanisms

3. Output Management

Output management includes:

  • User management - handling user sessions and maintaining connection state
  • Output formatting - structuring message data for presentation or further processing
  • User experience - ensuring smooth data flow and responsive application behavior
  • Performance optimization - maximizing message efficiency and minimizing resource usage

Common Response Codes

Success Response Codes

  • NORMAL (0): Message operation completed successfully - messaging was completed without errors
  • MSG (4): Message operation completed - operation completed with message-specific status

Error Response Codes

  • INVREQ (16): Invalid request - the message operation parameters are incorrect or unauthorized
  • NOTFND (20): Resource not found - the specified message resource does not exist
  • LENGERR (22): Length error - the message data length exceeds expected limits
  • MSG (24): Message error - a message-specific error occurred during the operation

Best Practices

1. Message Preparation

  • Prepare message appropriately - ensure all necessary resources and configurations are in place
  • Validate message content - verify that message data meets expected format and quality standards
  • Handle different message types - implement flexible processing to accommodate various messaging formats
  • Ensure message integrity - maintain data consistency and prevent corruption during messaging

2. Error Handling

  • Check all response codes - always examine both RESP and RESP2 for complete error information
  • Handle message failures - implement appropriate recovery mechanisms for failed message operations
  • Implement retry logic - provide automatic retry capabilities for transient failures
  • Log error conditions - maintain detailed logs for troubleshooting and monitoring purposes

3. Performance Optimization

  • Minimize message operations - reduce unnecessary message calls to improve overall performance
  • Use efficient message formats - choose appropriate data formats to minimize processing overhead
  • Optimize user updates - streamline user interface updates to reduce response time
  • Manage user resources - efficiently allocate and manage system resources for message operations

Explain It Like I'm 5 Years Old

Imagine you're sending a letter to a friend:

When you want to send a letter to a friend, you write the letter and put it in an envelope. If you send the letter, your friend gets it. If you don't send the letter, your friend doesn't get it.

CICS MSG is like sending a letter to a friend. The computer program writes a message and puts it in a special envelope. If it sends the message, the other computer gets it. If it doesn't send the message, the other computer doesn't get it.

Just like you send letters to friends, the computer program sends messages to other computers!

Exercises

Exercise 1: Message Operation

Write a CICS MSG command to perform a message operation.

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EXEC CICS MSG
    RESP(WS-RESPONSE)
    RESP2(WS-RESPONSE2)
END-EXEC.

Exercise 2: Message Processing

How would you implement comprehensive message processing that handles different message types and requirements?

Answer: Identify different message types and appropriate handling, implement message validation and encoding, handle different message types and capabilities, implement proper error handling for message failures, optimize message operations for performance, and maintain message integrity throughout the process.

Quiz

Question 1

What is the primary purpose of CICS MSG?

Answer: B) To provide message management capabilities

Question 2

Which parameter specifies the response code?

Answer: A) RESP

Related Concepts

CICS Message Processing

Message processing and output in CICS

CICS User Management

User management and user interaction in CICS

CICS Output Processing

Output processing and message display in CICS