COBOL Tutorial

COBOL RESET Clause - Quick Reference

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Overview

The RESET clause is used in COBOL file handling to reset file status and position indicators to their initial state. This is useful for error recovery and file reuse scenarios.

Purpose and Usage

Error recovery - Clear file status errors
File reuse - Reset file for multiple operations
Status clearing - Clear file status indicators
Position reset - Reset file position indicators
Debugging - Clear status for testing

RESET vs CLOSE Concept

RESET: [Status Clearing] → [File Reuse]

CLOSE: [Resource Release] → [File Termination]

RESET clears status, CLOSE releases resources

RESET clause enables file reuse by clearing status indicators.

Syntax

The RESET clause follows specific syntax patterns within file handling operations and can be used with different file types.

Basic Syntax

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* Basic RESET clause syntax
RESET file-name
    ...
 
RESET file-status-variable
    ...
 
* Complete example
RESET CUSTOMER-FILE
    ON EXCEPTION
        DISPLAY "Reset failed for customer file"
    NOT ON EXCEPTION
        DISPLAY "Customer file reset successfully".
 
* With error handling
RESET TRANSACTION-FILE
    ON EXCEPTION
        PERFORM HANDLE-RESET-ERROR
    NOT ON EXCEPTION
        PERFORM CONTINUE-PROCESSING.
 
* Multiple file reset
RESET INPUT-FILE, OUTPUT-FILE
    ON EXCEPTION
        DISPLAY "Reset failed for one or more files".

RESET clause clears file status and position indicators.

RESET vs CLOSE Comparison

Aspect	RESET	CLOSE
Purpose	Status clearing	Resource release
File state	Remains open	Closed
Reuse	Immediate	Requires reopen
Error recovery	Clears errors	Terminates access
Performance	Fast	Moderate

PROCEDURE DIVISION Structure

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* Complete PROCEDURE DIVISION with RESET
PROCEDURE DIVISION.
MAIN-LOGIC.
    PERFORM INITIALIZATION
    PERFORM PROCESS-FILES
    PERFORM FINALIZATION
    STOP RUN.
 
INITIALIZATION.
    OPEN INPUT CUSTOMER-FILE
    OPEN OUTPUT REPORT-FILE.
 
PROCESS-FILES.
    PERFORM UNTIL END-OF-FILE
        READ CUSTOMER-FILE
           AT END
              MOVE "Y" TO EOF-FLAG
           NOT AT END
              PERFORM PROCESS-RECORD
           ON EXCEPTION
              PERFORM HANDLE-READ-ERROR
        END-READ
    END-PERFORM.
 
HANDLE-READ-ERROR.
    * Reset file status and retry
    RESET CUSTOMER-FILE
    DISPLAY "File reset, retrying read operation".
 
FINALIZATION.
    CLOSE CUSTOMER-FILE
    CLOSE REPORT-FILE.

RESET clause is used within PROCEDURE DIVISION for error recovery.

Practical Examples

These examples demonstrate how to use the RESET clause effectively in different file handling scenarios.

Error Recovery with RESET

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IDENTIFICATION DIVISION.
PROGRAM-ID. ERROR-RECOVERY.
 
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT CUSTOMER-FILE ASSIGN TO "CUSTFILE.DAT"
        ORGANIZATION IS SEQUENTIAL
        ACCESS MODE IS SEQUENTIAL
        FILE STATUS IS CUSTOMER-STATUS.
 
DATA DIVISION.
FILE SECTION.
FD  CUSTOMER-FILE
    LABEL RECORDS ARE STANDARD
    RECORD CONTAINS 80 CHARACTERS.
01  CUSTOMER-RECORD.
    05  CUSTOMER-ID       PIC 9(6).
    05  CUSTOMER-NAME     PIC X(30).
    05  CUSTOMER-ADDRESS  PIC X(40).
    05  FILLER            PIC X(4).
 
WORKING-STORAGE SECTION.
01  CUSTOMER-STATUS       PIC XX.
01  EOF-FLAG              PIC X VALUE 'N'.
    88  END-OF-FILE         VALUE 'Y'.
01  ERROR-COUNT           PIC 9(3) VALUE 0.
01  MAX-ERRORS            PIC 9(3) VALUE 5.
 
PROCEDURE DIVISION.
MAIN-LOGIC.
    PERFORM INITIALIZATION
    PERFORM PROCESS-FILE UNTIL END-OF-FILE OR ERROR-COUNT >= MAX-ERRORS
    PERFORM FINALIZATION
    STOP RUN.
 
INITIALIZATION.
    OPEN INPUT CUSTOMER-FILE
    IF CUSTOMER-STATUS NOT = "00"
        DISPLAY "Error opening file: " CUSTOMER-STATUS
        STOP RUN.
 
PROCESS-FILE.
    READ CUSTOMER-FILE
       AT END
          MOVE "Y" TO EOF-FLAG
       NOT AT END
          PERFORM PROCESS-RECORD
       ON EXCEPTION
          PERFORM HANDLE-READ-ERROR
    END-READ.
 
HANDLE-READ-ERROR.
    ADD 1 TO ERROR-COUNT
    DISPLAY "Read error: " CUSTOMER-STATUS " - Attempt " ERROR-COUNT
    
    * Reset file status and retry
    RESET CUSTOMER-FILE
    IF CUSTOMER-STATUS = "00"
        DISPLAY "File reset successfully, continuing..."
    ELSE
        DISPLAY "Reset failed: " CUSTOMER-STATUS
        MOVE "Y" TO EOF-FLAG
    END-IF.
 
PROCESS-RECORD.
    * Process the customer record
    DISPLAY "Processing customer: " CUSTOMER-NAME.
 
FINALIZATION.
    CLOSE CUSTOMER-FILE
    DISPLAY "Processing complete. Errors: " ERROR-COUNT.

RESET clause enables error recovery in file processing.

File Reuse with RESET

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* File reuse scenario with RESET
PROCEDURE DIVISION.
BATCH-PROCESSING.
    PERFORM INITIALIZATION
    PERFORM PROCESS-BATCH-1
    PERFORM RESET-FOR-BATCH-2
    PERFORM PROCESS-BATCH-2
    PERFORM FINALIZATION
    STOP RUN.
 
INITIALIZATION.
    OPEN INPUT DATA-FILE
    OPEN OUTPUT REPORT-FILE.
 
PROCESS-BATCH-1.
    DISPLAY "Processing batch 1..."
    PERFORM UNTIL BATCH-1-COMPLETE
        READ DATA-FILE
           AT END
              MOVE "Y" TO BATCH-1-COMPLETE
           NOT AT END
              PERFORM PROCESS-BATCH-1-RECORD
        END-READ
    END-PERFORM.
 
RESET-FOR-BATCH-2.
    DISPLAY "Resetting file for batch 2..."
    RESET DATA-FILE
    IF FILE-STATUS = "00"
        DISPLAY "File reset successfully for batch 2"
    ELSE
        DISPLAY "Reset failed: " FILE-STATUS
        STOP RUN
    END-IF.
 
PROCESS-BATCH-2.
    DISPLAY "Processing batch 2..."
    PERFORM UNTIL BATCH-2-COMPLETE
        READ DATA-FILE
           AT END
              MOVE "Y" TO BATCH-2-COMPLETE
           NOT AT END
              PERFORM PROCESS-BATCH-2-RECORD
        END-READ
    END-PERFORM.
 
PROCESS-BATCH-1-RECORD.
    * Process record for batch 1
    WRITE REPORT-RECORD FROM DATA-RECORD.
 
PROCESS-BATCH-2-RECORD.
    * Process record for batch 2 with different logic
    MOVE DATA-RECORD TO BATCH-2-RECORD
    PERFORM VALIDATE-BATCH-2
    IF VALID-RECORD
        WRITE REPORT-RECORD FROM BATCH-2-RECORD
    END-IF.
 
FINALIZATION.
    CLOSE DATA-FILE
    CLOSE REPORT-FILE.

RESET clause enables file reuse for multiple batch operations.

Multiple File Reset

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* Multiple file reset scenario
PROCEDURE DIVISION.
MULTI-FILE-PROCESSING.
    PERFORM INITIALIZATION
    PERFORM PROCESS-MULTIPLE-FILES
    PERFORM RESET-ALL-FILES
    PERFORM REPROCESS-FILES
    PERFORM FINALIZATION
    STOP RUN.
 
INITIALIZATION.
    OPEN INPUT FILE-1, FILE-2, FILE-3
    OPEN OUTPUT OUTPUT-FILE.
 
PROCESS-MULTIPLE-FILES.
    DISPLAY "Processing multiple files..."
    PERFORM UNTIL ALL-FILES-PROCESSED
        PERFORM READ-AND-PROCESS-FILES
    END-PERFORM.
 
READ-AND-PROCESS-FILES.
    READ FILE-1
       AT END
          MOVE "Y" TO FILE-1-EOF
       NOT AT END
          PERFORM PROCESS-FILE-1-RECORD
       ON EXCEPTION
          PERFORM HANDLE-FILE-1-ERROR
    END-READ
    
    READ FILE-2
       AT END
          MOVE "Y" TO FILE-2-EOF
       NOT AT END
          PERFORM PROCESS-FILE-2-RECORD
       ON EXCEPTION
          PERFORM HANDLE-FILE-2-ERROR
    END-READ
    
    READ FILE-3
       AT END
          MOVE "Y" TO FILE-3-EOF
       NOT AT END
          PERFORM PROCESS-FILE-3-RECORD
       ON EXCEPTION
          PERFORM HANDLE-FILE-3-ERROR
    END-READ.
 
RESET-ALL-FILES.
    DISPLAY "Resetting all files..."
    RESET FILE-1, FILE-2, FILE-3
    IF FILE-1-STATUS = "00" AND FILE-2-STATUS = "00" AND FILE-3-STATUS = "00"
        DISPLAY "All files reset successfully"
    ELSE
        DISPLAY "One or more files failed to reset"
        STOP RUN
    END-IF.
 
REPROCESS-FILES.
    DISPLAY "Reprocessing files..."
    PERFORM UNTIL ALL-FILES-REPROCESSED
        PERFORM READ-AND-REPROCESS-FILES
    END-PERFORM.
 
FINALIZATION.
    CLOSE FILE-1, FILE-2, FILE-3
    CLOSE OUTPUT-FILE.

RESET clause enables multiple file reset for batch processing.

Debugging with RESET

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* Debugging scenario with RESET
PROCEDURE DIVISION.
DEBUG-PROCESSING.
    PERFORM INITIALIZATION
    PERFORM DEBUG-FILE-OPERATIONS
    PERFORM FINALIZATION
    STOP RUN.
 
INITIALIZATION.
    OPEN INPUT DEBUG-FILE
    OPEN OUTPUT DEBUG-LOG.
 
DEBUG-FILE-OPERATIONS.
    DISPLAY "Starting debug file operations..."
    
    * First read operation
    READ DEBUG-FILE
       NOT AT END
          DISPLAY "First read successful"
          PERFORM LOG-SUCCESS
       ON EXCEPTION
          DISPLAY "First read failed: " FILE-STATUS
          PERFORM LOG-ERROR
    END-READ
    
    * Reset file status for clean testing
    RESET DEBUG-FILE
    DISPLAY "File reset for second test"
    
    * Second read operation
    READ DEBUG-FILE
       NOT AT END
          DISPLAY "Second read successful"
          PERFORM LOG-SUCCESS
       ON EXCEPTION
          DISPLAY "Second read failed: " FILE-STATUS
          PERFORM LOG-ERROR
    END-READ
    
    * Reset again for third test
    RESET DEBUG-FILE
    DISPLAY "File reset for third test"
    
    * Third read operation
    READ DEBUG-FILE
       NOT AT END
          DISPLAY "Third read successful"
          PERFORM LOG-SUCCESS
       ON EXCEPTION
          DISPLAY "Third read failed: " FILE-STATUS
          PERFORM LOG-ERROR
    END-READ.
 
LOG-SUCCESS.
    WRITE DEBUG-LOG-RECORD FROM "SUCCESS: File operation completed".
 
LOG-ERROR.
    WRITE DEBUG-LOG-RECORD FROM "ERROR: File operation failed".
 
FINALIZATION.
    CLOSE DEBUG-FILE
    CLOSE DEBUG-LOG.

RESET clause enables clean debugging by clearing file status.

Best Practices and Tips

Following these best practices ensures effective use of the RESET clause in COBOL applications.

RESET Best Practices

Check file status after RESET - Verify reset was successful
Use for error recovery - Clear errors before retrying
Implement proper error handling - Address root causes
Test with different file types - Verify behavior
Document reset operations - Record when and why RESET is used
Monitor performance impact - Ensure RESET doesn't cause issues

Common Pitfalls to Avoid

Pitfall	Problem	Solution
Not checking status after RESET	Unreliable error recovery	Always verify RESET success
Using RESET instead of fixing errors	Masking real problems	Address root causes
Excessive RESET usage	Performance degradation	Use RESET judiciously
Not testing with all file types	Unexpected behavior	Test thoroughly
Ignoring RESET failures	Continued errors	Handle RESET failures

Performance Considerations

Fast operation - RESET is typically very fast
Minimal overhead - Little impact on performance
Memory efficient - Doesn't allocate new resources
Error recovery - Enables continued processing
File reuse - Avoids reopen overhead

When to Use RESET vs Other Methods

Scenario	Use RESET	Use Other Methods
Error recovery	Yes	No
File reuse	Yes	No
Status clearing	Yes	No
File termination	No	Yes (CLOSE)
Resource release	No	Yes (CLOSE)

RESET Clause Quick Reference

Usage	Syntax	Purpose
Single file reset	RESET file-name	Reset one file
Multiple file reset	RESET file1, file2	Reset multiple files
With error handling	RESET file ON EXCEPTION	Handle reset errors
Status variable reset	RESET status-var	Reset status indicators
Position reset	RESET position-indicator	Reset position indicators

Test Your Knowledge

1. What is the primary purpose of the RESET clause in COBOL?

To create new files
To reset file status and position indicators
To generate reset reports
To create program documentation

2. In which context is the RESET clause most commonly used?

FILE SECTION
PROCEDURE DIVISION
WORKING-STORAGE SECTION
ENVIRONMENT DIVISION

3. What happens when a RESET clause is executed?

File status is reset to initial state
File status and position indicators are reset
A reset file is created
Reset data is processed

4. What is the relationship between RESET and file status?

They are unrelated
RESET clears file status indicators
RESET is faster than other methods
They cannot be used together

5. Which of the following is a valid RESET clause usage?

RESET file-name
RESET file-status
RESET position-indicator
All of the above

Frequently Asked Questions

Related Concepts

File Processing

Complete guide to COBOL file processing operations.

Error Handling

Using error handling techniques in COBOL.

CLOSE Statement

Using CLOSE to terminate file operations.

OPEN Statement

Using OPEN to start file operations.

File Status Error Handling

Handling file status errors in COBOL.

RESERVE Clause RETURN and END-RETURN

COBOL Tutorial

COBOL RESET Clause - Quick Reference

Overview

Purpose and Usage

RESET vs CLOSE Concept

Syntax

Basic Syntax

RESET vs CLOSE Comparison

PROCEDURE DIVISION Structure

Practical Examples

Error Recovery with RESET

File Reuse with RESET

Multiple File Reset

Debugging with RESET

Best Practices and Tips

RESET Best Practices

Common Pitfalls to Avoid

Performance Considerations

When to Use RESET vs Other Methods

RESET Clause Quick Reference

Test Your Knowledge

Frequently Asked Questions

What is the difference between RESET and CLOSE in COBOL file handling?

How does the RESET clause affect file processing and error recovery?

Can you use RESET with all types of files in COBOL?

What are some common use cases for the RESET clause?

How do you handle errors and debugging when using the RESET clause?

Related Concepts

File Processing

Error Handling

CLOSE Statement

OPEN Statement

File Status Error Handling

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