JCL Utility Programs

Purpose

JCL Utility Programs are system-provided applications designed to perform common data management and file manipulation tasks. These utilities enable standardized operations without requiring custom programming, ensuring consistent, reliable execution of routine functions.

Common IBM Utility Programs

Detailed Program Overviews

IEFBR14 (Dummy Program)

IEFBR14 is a minimal program that does nothing but return control to the system with a return code of zero. Its primary purpose is to leverage JCL DD statement functions (allocation, deletion, catalog management) without actually processing data.

Key Characteristics:

• Contains only a single assembler instruction: BR 14 (Branch to Register 14)
• Takes no input, produces no output
• Used exclusively for dataset operations through DD statement DISP parameters

Common Usage Examples:

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//STEP1    EXEC PGM=IEFBR14
//CREATE   DD DSN=USER.NEW.DATASET,
//            DISP=(NEW,CATLG,DELETE),
//            SPACE=(TRK,(10,2)),
//            DCB=(RECFM=FB,LRECL=80,BLKSIZE=27920)
//DELETE   DD DSN=USER.OLD.DATASET,
//            DISP=(MOD,DELETE,DELETE)

This example creates a new dataset and deletes an old dataset without processing any data. The IEFBR14 program itself does nothing; all actions occur through JCL DD statement disposition processing.

IEBGENER (Sequential Copy Utility)

IEBGENER copies sequential datasets with optional modifications such as record selection, field manipulation, or format conversion.

Key DD Statements:

• SYSUT1 - Input dataset (required)
• SYSUT2 - Output dataset (required)
• SYSIN - Control statements (optional, DUMMY if not needed)
• SYSPRINT - Message output (required)

Common Usage Example:

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//STEP2    EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1   DD DSN=USER.INPUT.DATASET,DISP=SHR
//SYSUT2   DD DSN=USER.OUTPUT.DATASET,
//            DISP=(NEW,CATLG,DELETE),
//            SPACE=(TRK,(5,2)),
//            DCB=(RECFM=FB,LRECL=80,BLKSIZE=27920)
//SYSIN    DD DUMMY

This example copies USER.INPUT.DATASET to a new dataset called USER.OUTPUT.DATASET without making any changes to the data.

IDCAMS (Access Method Services)

IDCAMS is a versatile utility for managing VSAM datasets, catalogs, and performing various data management functions through powerful command statements.

Key DD Statements:

• SYSPRINT - Message output (required)
• SYSIN - Control statements (required)
• Additional DD statements as required by specific commands

Common Commands:

• DEFINE - Create VSAM datasets and catalogs
• DELETE - Remove VSAM datasets and catalogs
• PRINT - Display dataset contents
• REPRO - Copy or convert datasets
• LISTCAT - Display catalog information
• ALTER - Change dataset attributes

Common Usage Example:

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//STEP3    EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN    DD *
  DELETE USER.VSAM.KSDS CLUSTER PURGE
  DEFINE CLUSTER -
         (NAME(USER.VSAM.KSDS) -
          INDEXED -
          RECORDSIZE(100 200) -
          KEYS(10 0) -
          VOLUMES(VOLSER) -
          CYLINDERS(2 1)) -
     DATA (NAME(USER.VSAM.KSDS.DATA)) -
     INDEX (NAME(USER.VSAM.KSDS.INDEX))
  LISTCAT ENTRIES(USER.VSAM.KSDS) ALL
/*

This example deletes an existing VSAM Key-Sequenced Data Set (KSDS), defines a new one, and then lists the catalog entry for verification.

DFSORT (Sort, Merge, Copy Utility)

DFSORT is a high-performance data processing utility used for sorting, merging, copying, and transforming data.

Key DD Statements:

• SORTIN - Input dataset for SORT (required for SORT)
• SORTINnn - Input datasets for MERGE (required for MERGE)
• SORTOUT - Output dataset (required)
• SYSIN - Control statements (required)
• SYSOUT - Message output (required)

Common Usage Example:

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//STEP4    EXEC PGM=SORT
//SYSOUT   DD SYSOUT=*
//SORTIN   DD DSN=USER.UNSORTED.DATA,DISP=SHR
//SORTOUT  DD DSN=USER.SORTED.DATA,
//            DISP=(NEW,CATLG,DELETE),
//            SPACE=(CYL,(5,2)),
//            DCB=(RECFM=FB,LRECL=100,BLKSIZE=32700)
//SYSIN    DD *
  SORT FIELDS=(10,5,CH,A,25,3,BI,D)
  INCLUDE COND=(5,2,CH,EQ,C'NY')
  OUTREC FIELDS=(1,20,35,15,21,10)
/*

This example sorts a dataset based on a character field at position 10 (ascending) and a binary field at position 25 (descending), includes only records with 'NY' in positions 5-6, and restructures the output records.

Utility Selection Guidelines

Choosing the right utility for a specific task improves efficiency and reduces complexity:

Performance Considerations

• IEBGENER vs. ICEGENER: ICEGENER automatically invokes DFSORT for better performance when possible; use it instead of IEBGENER
• Block sizes: Use system-determined block sizes (SDB) or optimal block sizes for improved I/O performance
• DFSORT options: Adjust SORT parameters for memory usage based on dataset size (DYNALLOC, FILSZ)
• IDCAMS SPEED vs. RECOVERY: Use SPEED option for faster VSAM definition when recovery is not critical
• VIO vs. physical datasets: For small temporary files, VIO (Virtual I/O) can improve performance

Common Issues and Troubleshooting

Advanced Techniques

IDCAMS Parameter Files

For complex operations, store IDCAMS commands in a separate dataset:

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//STEP5    EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN    DD DSN=USER.IDCAMS.COMMANDS,DISP=SHR

Conditional Execution Based on Utility Return Codes

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//STEP6    EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN    DD *
  DELETE USER.TEST.FILE
/*
//STEP7    EXEC PGM=IEFBR14,COND=(4,LT,STEP6)
//NEWDD    DD DSN=USER.TEST.FILE,
//            DISP=(NEW,CATLG,DELETE),
//            SPACE=(TRK,(1,1))

This example creates a new dataset only if the DELETE command in the previous step returned a code less than 4 (successful deletion or file did not exist).

Using DFSORT for Complex Data Transformation

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//STEP8    EXEC PGM=SORT
//SYSOUT   DD SYSOUT=*
//SORTIN   DD DSN=USER.INPUT.DATA,DISP=SHR
//SORTOUT  DD DSN=USER.REPORT.DATA,
//            DISP=(NEW,CATLG,DELETE),
//            SPACE=(CYL,(1,1)),
//            DCB=(RECFM=FB,LRECL=132,BLKSIZE=27984)
//SYSIN    DD *
  SORT FIELDS=COPY
  OUTREC IFTHEN=(WHEN=(5,2,CH,EQ,C'NY'),
                 BUILD=(1,4,
                        C'NEW YORK',
                        15,20,
                        35X)),
         IFTHEN=(WHEN=(5,2,CH,EQ,C'CA'),
                 BUILD=(1,4,
                        C'CALIFORNIA',
                        15,20,
                        35X)),
         IFTHEN=(WHEN=NONE,
                 BUILD=(1,4,
                        C'OTHER STATE',
                        15,20,
                        35X))
/*

This example uses DFSORT's IFTHEN clauses to perform data transformation based on conditional logic, similar to a CASE statement in programming languages.

Best Practices

1. Use ICEGENER instead of IEBGENER for better performance with simple copying operations
2. Include appropriate REGION parameters for memory-intensive utilities like SORT and ADRDSSU
3. Handle return codes to manage conditional execution based on utility results
4. Document utility usage with JCL comments to explain the purpose of each step
5. Check utility-specific documentation for version-specific features and optimizations
6. Consider specialized vendor utilities for performance-critical operations
7. Standardize utility usage across applications for consistency and maintainability
8. Review utility output messages even for successful executions to identify potential issues
9. Use system symbolic parameters to make utility JCL more flexible and environment-independent

JES2 vs JES3 Considerations

Most utility programs work identically in JES2 and JES3 environments, but there are some considerations:

• JES3 provides additional dataset management capabilities through its catalog and setup phase
• JES3 has stronger dataset integrity controls which may affect utility behavior with shared datasets
• Utilities that use spool files may have performance differences between JES2 and JES3

Related Concepts

• DISP Parameter - Critical for IEFBR14 functionality
• DSN Parameter - Dataset naming for utilities
• SPACE Parameter - Allocation for utility output
• DCB Parameter - Dataset characteristics for utility processing
• COND Parameter - Conditional processing based on utility return codes
• PARM Parameter - Passing parameters to utility programs