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CICS READ - Read

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

What is CICS READ?

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

Command Syntax

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EXEC CICS READ
    [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 read 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

Read Types

1. Basic Reads

  • Basic reads: Standard read operations that handle simple reading without special formatting
  • Mapped reads: Read operations that use predefined field mappings to structure read data
  • Unmapped reads: Raw read operations that handle unstructured reading without predefined field mappings
  • Custom reads: Specialized read operations designed for specific application requirements

2. Advanced Reads

  • Advanced reads: Complex read operations that handle sophisticated reading processing and validation
  • Secure reads: Read operations that include encryption and security features for sensitive reading
  • Encrypted reads: Read operations that automatically encrypt read data
  • Compressed reads: Read operations that handle compressed reading streams and automatically compress read data

3. Specialized Reads

  • Specialized reads: Read operations tailored for specific protocols or communication methods
  • High-performance reads: Optimized read operations designed for maximum throughput and efficiency
  • Low-latency reads: Read operations optimized for minimal delay and real-time processing requirements
  • High-throughput reads: Read operations designed to handle large volumes of reading 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.
    * Read operation
    EXEC CICS READ
        RESP(WS-RESPONSE)
        RESP2(WS-RESPONSE2)
    END-EXEC.
    
    IF WS-RESPONSE NOT EQUAL DFHRESP(NORMAL)
        EXEC CICS WRITE OPERATOR
            TEXT('READ command failed')
        END-EXEC
        EXEC CICS RETURN END-EXEC
    END-IF.
    
    * Read operation completed successfully
    * Continue processing

Read Processing

1. Read Preparation

Read preparation includes:

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

2. Read Transmission

Read transmission includes:

  • Read routing - directing read data to the appropriate processing location
  • Read delivery - ensuring read data reaches the correct destination within the application
  • Transmission confirmation - verifying that read 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 read data for presentation or further processing
  • User experience - ensuring smooth data flow and responsive application behavior
  • Performance optimization - maximizing read efficiency and minimizing resource usage

Common Response Codes

Success Response Codes

  • NORMAL (0): Read operation completed successfully - reading was completed without errors
  • READ (4): Read operation completed - operation completed with read-specific status

Error Response Codes

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

Best Practices

1. Read Preparation

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

2. Error Handling

  • Check all response codes - always examine both RESP and RESP2 for complete error information
  • Handle read failures - implement appropriate recovery mechanisms for failed read 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 read operations - reduce unnecessary read calls to improve overall performance
  • Use efficient read 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 read operations

Explain It Like I'm 5 Years Old

Imagine you're reading a book:

When you want to read a book, you open it and look at the words. If you read the book, you learn what it says. If you don't read the book, you don't learn what it says.

CICS READ is like reading a book. The computer program opens a file and looks at the data. If it reads the file, it learns what it says. If it doesn't read the file, it doesn't learn what it says.

Just like you read books, the computer program reads files!

Exercises

Exercise 1: Read Operation

Write a CICS READ command to perform a read operation.

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

Exercise 2: Read Processing

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

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

Quiz

Question 1

What is the primary purpose of CICS READ?

Answer: B) To provide read management capabilities

Question 2

Which parameter specifies the response code?

Answer: A) RESP

Related Concepts

CICS Read Processing

Read processing and output in CICS

CICS User Management

User management and user interaction in CICS

CICS Output Processing

Output processing and read display in CICS