COBOL Tutorial

COBOL REORG-CRITERIA Clause - Quick Reference

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Overview

The REORG-CRITERIA clause is used to specify parameters for VSAM file reorganization operations. It controls how VSAM files are optimized during reorganization to improve performance and storage efficiency.

Purpose and Usage

VSAM optimization - Optimize VSAM file structure and performance
Space management - Control free space allocation and utilization
Performance tuning - Improve access patterns and I/O efficiency
Fragmentation reduction - Eliminate file fragmentation
Index optimization - Rebuild and optimize index structures

VSAM Reorganization Concept

Before: [Fragmented Data] [Poor Index] [Low Performance]

REORG-CRITERIA: [Optimization Parameters]

After: [Optimized Data] [Efficient Index] [High Performance]

Reorganization rebuilds file structure according to criteria

REORG-CRITERIA controls how VSAM files are rebuilt during reorganization.

Syntax

The REORG-CRITERIA clause follows specific syntax patterns for VSAM file reorganization and can include various optimization parameters.

Basic Syntax

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* Basic REORG-CRITERIA clause syntax
REORG-CRITERIA
    FREESPACE (data-percent, index-percent)
    RECORDSIZE (average, maximum)
    BLOCKSIZE (minimum, maximum)
    KEYLENGTH key-length
    INDEXED
    SEQUENTIAL
 
* Complete example
REORG-CRITERIA
    FREESPACE (20, 25)
    RECORDSIZE (100, 200)
    BLOCKSIZE (4096, 8192)
    KEYLENGTH 10
    INDEXED
 
* Alternative syntax for utility programs
//REPRO EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
    REPRO INFILE(INPUT.VSAM) OUTFILE(OUTPUT.VSAM)
    REORG-CRITERIA
        FREESPACE (15, 20)
        RECORDSIZE (80, 150)
        BLOCKSIZE (2048, 4096)
/*

REORG-CRITERIA specifies optimization parameters for VSAM reorganization.

REORG-CRITERIA vs File Definition Comparison

Aspect	REORG-CRITERIA	File Definition
Purpose	Reorganization optimization	File structure definition
Usage	Utility programs	Application programs
File type	VSAM files only	All file types
Timing	During reorganization	During file access
Impact	Performance optimization	Data access

Common REORG-CRITERIA Parameters

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* FREESPACE parameter
REORG-CRITERIA
    FREESPACE (data-percent, index-percent)
    * Example: 20% free space in data, 25% in index
    FREESPACE (20, 25)
 
* RECORDSIZE parameter
REORG-CRITERIA
    RECORDSIZE (average-size, maximum-size)
    * Example: Average 100 bytes, maximum 200 bytes
    RECORDSIZE (100, 200)
 
* BLOCKSIZE parameter
REORG-CRITERIA
    BLOCKSIZE (minimum-size, maximum-size)
    * Example: Minimum 2048, maximum 8192 bytes
    BLOCKSIZE (2048, 8192)
 
* KEYLENGTH parameter
REORG-CRITERIA
    KEYLENGTH key-length
    * Example: 10-byte keys
    KEYLENGTH 10
 
* File type indicators
REORG-CRITERIA
    INDEXED    * For KSDS files
    SEQUENTIAL * For ESDS files
    RELATIVE   * For RRDS files

Different parameters control various aspects of VSAM reorganization.

Practical Examples

These examples demonstrate how to use the REORG-CRITERIA clause effectively in different VSAM reorganization scenarios.

Customer Master File Reorganization

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* Customer master file reorganization
//REORG1 EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
    REPRO INFILE(CUSTOMER.MASTER) OUTFILE(CUSTOMER.NEW)
    REORG-CRITERIA
        FREESPACE (15, 20)
        RECORDSIZE (200, 250)
        BLOCKSIZE (4096, 8192)
        KEYLENGTH 10
        INDEXED
/*
//REORG2 EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
    DELETE CUSTOMER.MASTER
    RENAME CUSTOMER.NEW CUSTOMER.MASTER
/*
 
* Alternative using DFSMS utilities
//REORG3 EXEC PGM=DFSMSTVS
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
    REORG DATASET(CUSTOMER.MASTER)
    REORG-CRITERIA
        FREESPACE (15, 20)
        RECORDSIZE (200, 250)
        BLOCKSIZE (4096, 8192)
        KEYLENGTH 10
        INDEXED
    END
/*

REORG-CRITERIA optimizes customer master file for better performance.

Transaction File Optimization

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* High-volume transaction file reorganization
//TXNREORG EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
    REPRO INFILE(TRANSACTION.FILE) OUTFILE(TRANSACTION.NEW)
    REORG-CRITERIA
        FREESPACE (10, 15)        * Lower free space for high volume
        RECORDSIZE (150, 180)     * Optimized for transaction records
        BLOCKSIZE (8192, 16384)   * Larger blocks for better I/O
        KEYLENGTH 8               * Transaction ID length
        INDEXED
/*
//CLEANUP EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
    DELETE TRANSACTION.FILE
    RENAME TRANSACTION.NEW TRANSACTION.FILE
/*
 
* Performance monitoring after reorganization
//PERFMON EXEC PGM=VSAMSTAT
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
    STATS DATASET(TRANSACTION.FILE)
    REPORT PERFORMANCE
/*

Transaction files benefit from optimized REORG-CRITERIA for high-volume processing.

Sequential File Reorganization

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* ESDS (Entry Sequenced Data Set) reorganization
//ESDSREORG EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
    REPRO INFILE(LOG.FILE) OUTFILE(LOG.NEW)
    REORG-CRITERIA
        FREESPACE (5, 0)          * Minimal free space for logs
        RECORDSIZE (80, 120)      * Log record sizes
        BLOCKSIZE (2048, 4096)    * Standard block sizes
        SEQUENTIAL               * ESDS file type
/*
//SWAP EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
    DELETE LOG.FILE
    RENAME LOG.NEW LOG.FILE
/*
 
* Relative Record Data Set reorganization
//RRDSREORG EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
    REPRO INFILE(LOOKUP.TABLE) OUTFILE(LOOKUP.NEW)
    REORG-CRITERIA
        FREESPACE (20, 0)         * Free space for future expansion
        RECORDSIZE (50, 50)       * Fixed-size lookup records
        BLOCKSIZE (1024, 2048)    * Small blocks for random access
        RELATIVE                 * RRDS file type
/*

Different VSAM file types require different REORG-CRITERIA settings.

Performance Tuning Examples

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* High-performance read-optimized file
//READOPT EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
    REPRO INFILE(REFERENCE.DATA) OUTFILE(REFERENCE.NEW)
    REORG-CRITERIA
        FREESPACE (5, 10)         * Minimal free space for reads
        RECORDSIZE (300, 400)     * Large reference records
        BLOCKSIZE (16384, 32768)  * Large blocks for sequential reads
        KEYLENGTH 15              * Reference key length
        INDEXED
/*
 
* Write-optimized file with frequent inserts
//WRITEOPT EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
    REPRO INFILE(ACTIVE.DATA) OUTFILE(ACTIVE.NEW)
    REORG-CRITERIA
        FREESPACE (30, 35)        * High free space for inserts
        RECORDSIZE (100, 150)     * Variable transaction records
        BLOCKSIZE (4096, 8192)    * Moderate block sizes
        KEYLENGTH 12              * Transaction key length
        INDEXED
/*
 
* Balanced performance for mixed workload
//BALANCED EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
    REPRO INFILE(GENERAL.DATA) OUTFILE(GENERAL.NEW)
    REORG-CRITERIA
        FREESPACE (20, 25)        * Balanced free space
        RECORDSIZE (200, 250)     * Typical record sizes
        BLOCKSIZE (8192, 16384)   * Balanced block sizes
        KEYLENGTH 10              * Standard key length
        INDEXED
/*

REORG-CRITERIA can be tuned for specific performance requirements.

Performance and Best Practices

Understanding performance implications and best practices ensures effective use of the REORG-CRITERIA clause.

Performance Considerations

FREESPACE impact - Higher values improve insert performance but reduce storage efficiency
BLOCKSIZE optimization - Larger blocks improve sequential access but may waste memory
RECORDSIZE accuracy - Accurate sizing improves space utilization and performance
KEYLENGTH optimization - Proper key length affects index performance
Reorganization frequency - Regular reorganization maintains optimal performance

Optimization Strategies

Strategy	Benefit	Implementation
Read optimization	Faster sequential access	Large blocks, low free space
Write optimization	Better insert performance	High free space, moderate blocks
Space efficiency	Reduced storage usage	Low free space, accurate sizing
Mixed workload	Balanced performance	Moderate settings
High availability	Reduced reorganization needs	Conservative settings

Best Practices

Monitor file statistics - Track fragmentation and performance metrics
Schedule regular reorganization - Prevent performance degradation
Test reorganization settings - Verify performance improvements
Document criteria settings - Maintain configuration records
Consider workload patterns - Align settings with usage patterns
Plan for growth - Account for future data volume increases

Common Pitfalls to Avoid

Pitfall	Problem	Solution
Excessive free space	Wasted storage	Balance with usage patterns
Incorrect record sizes	Poor space utilization	Analyze actual record sizes
Inappropriate block sizes	Poor I/O performance	Match to access patterns
Infrequent reorganization	Performance degradation	Schedule regular reorganization
Ignoring workload changes	Suboptimal performance	Monitor and adjust settings

REORG-CRITERIA Quick Reference

Parameter	Syntax	Purpose
FREESPACE	FREESPACE (data%, index%)	Control free space allocation
RECORDSIZE	RECORDSIZE (avg, max)	Specify record size parameters
BLOCKSIZE	BLOCKSIZE (min, max)	Define block size range
KEYLENGTH	KEYLENGTH length	Specify key length
File type	INDEXED/SEQUENTIAL/RELATIVE	Indicate VSAM file type

Test Your Knowledge

1. What is the primary purpose of the REORG-CRITERIA clause in COBOL?

To reorganize program structure
To specify VSAM file reorganization criteria
To reorganize data in memory
To reorganize JCL procedures

2. In which type of file operations is REORG-CRITERIA most commonly used?

Sequential files
VSAM files
Indexed files
Relative files

3. What happens during a VSAM reorganization operation?

Data is deleted and recreated
File structure is optimized and rebuilt
Records are sorted in a new order
File is copied to a new location

4. What is the relationship between REORG-CRITERIA and file performance?

No relationship
REORG-CRITERIA improves file performance
REORG-CRITERIA decreases file performance
REORG-CRITERIA only affects storage usage

5. Which of the following is a valid REORG-CRITERIA parameter?

FREESPACE
RECORDSIZE
BLOCKSIZE
All of the above

COBOL Tutorial

COBOL REORG-CRITERIA Clause - Quick Reference

Overview

Purpose and Usage

VSAM Reorganization Concept

Syntax

Basic Syntax

REORG-CRITERIA vs File Definition Comparison

Common REORG-CRITERIA Parameters

Practical Examples

Customer Master File Reorganization

Transaction File Optimization

Sequential File Reorganization

Performance Tuning Examples

Performance and Best Practices

Performance Considerations

Optimization Strategies

Best Practices

Common Pitfalls to Avoid

REORG-CRITERIA Quick Reference

Test Your Knowledge

Frequently Asked Questions

Related Concepts

VSAM Concepts

File Organization Types

Performance Optimization

File Status and Error Handling

Mainframe Environment

Related Pages

COBOL Tutorial

COBOL REORG-CRITERIA Clause - Quick Reference

Overview

Purpose and Usage

VSAM Reorganization Concept

Syntax

Basic Syntax

REORG-CRITERIA vs File Definition Comparison

Common REORG-CRITERIA Parameters

Practical Examples

Customer Master File Reorganization

Transaction File Optimization

Sequential File Reorganization

Performance Tuning Examples

Performance and Best Practices

Performance Considerations

Optimization Strategies

Best Practices

Common Pitfalls to Avoid

REORG-CRITERIA Quick Reference

Test Your Knowledge

Frequently Asked Questions

What is the difference between REORG-CRITERIA and regular file definition clauses?

How does REORG-CRITERIA affect VSAM file performance and storage efficiency?

Can you use REORG-CRITERIA with all VSAM file types?

What are some common REORG-CRITERIA parameters and their purposes?

How do you determine the optimal REORG-CRITERIA settings for a specific VSAM file?

Related Concepts

VSAM Concepts

File Organization Types

Performance Optimization

File Status and Error Handling

Mainframe Environment

Related Pages