JCL Tutorial

IEBGENER Utility

Copy, convert, and manipulate sequential datasets efficiently

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Introduction to IEBGENER

IEBGENER is one of the most commonly used IBM utilities in mainframe JCL. Its primary function is to copy sequential datasets and members of partitioned datasets, optionally performing data conversion during the copy operation. The name "GENER" stands for "General" as it provides general-purpose data manipulation capabilities.

While simple in concept, IEBGENER is incredibly versatile and can handle a wide variety of data manipulation tasks including record format conversion, reblocking, character translation, and more.

Purpose and Function

IEBGENER provides several key functions for dataset manipulation:

Copy Datasets

Create an exact copy of a sequential dataset or a PDS member

Convert Record Formats

Change between fixed, variable, and undefined record formats

Reblock Records

Change block sizes to optimize I/O performance

Add or Remove Records

Insert new records or remove existing ones

Edit Records

Modify record content using control statements

Print Datasets

Convert datasets to printable format

Common Use Cases:

Copying data from one dataset to another
Converting legacy data formats to modern formats
Creating printable reports from raw data
Moving data between different storage devices
Generating test data from templates

IEBGENER JCL Requirements

To use IEBGENER, you need to include specific DD statements in your JCL. Each DD statement serves a specific purpose in the utility's operation.

Required DD Statements

DD Name	Purpose
SYSUT1	Input dataset to be copied
SYSUT2	Output dataset where the copied/converted data will be placed
SYSIN	Control statements (can be DUMMY if no control statements are needed)
SYSPRINT	Messages and diagnostics output

Basic IEBGENER JCL Example

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//COPY     EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1   DD DSN=INPUT.DATASET,DISP=SHR
//SYSUT2   DD DSN=OUTPUT.DATASET,DISP=(NEW,CATLG,DELETE),
//            UNIT=SYSDA,SPACE=(TRK,(10,5),RLSE)
//SYSIN    DD DUMMY

This simple example copies data from INPUT.DATASET to OUTPUT.DATASET without any modifications.

Copying and Converting Datasets

IEBGENER's most common use is straightforward dataset copying, but it's extremely powerful when you need to convert data characteristics during the copy process.

Simple Dataset Copy

To copy a dataset without any changes:

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//COPYSTEP EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1   DD DSN=MY.INPUT.DATA,DISP=SHR
//SYSUT2   DD DSN=MY.OUTPUT.DATA,DISP=(NEW,CATLG,DELETE),
//            UNIT=SYSDA,SPACE=(TRK,(5,2))
//SYSIN    DD DUMMY

Converting Record Format

To change the record format during copying:

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//CONVERT  EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1   DD DSN=MY.VB.DATASET,DISP=SHR
//SYSUT2   DD DSN=MY.FB.DATASET,DISP=(NEW,CATLG,DELETE),
//            UNIT=SYSDA,SPACE=(TRK,(5,2)),
//            DCB=(RECFM=FB,LRECL=80,BLKSIZE=27920)
//SYSIN    DD DUMMY

This example converts a variable-blocked (VB) dataset to fixed-blocked (FB) format.

Reblocking a Dataset

To change the block size for performance optimization:

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//REBLOCK  EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1   DD DSN=MY.ORIGINAL.DATA,DISP=SHR
//SYSUT2   DD DSN=MY.REBLOCKED.DATA,DISP=(NEW,CATLG,DELETE),
//            UNIT=SYSDA,SPACE=(TRK,(5,2)),
//            DCB=(BLKSIZE=32760)
//SYSIN    DD DUMMY

This example changes only the block size, optimizing it for better I/O performance.

Copying In-stream Data

To create a dataset from in-stream (inline) data:

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//INSTREAM EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1   DD *
This is line 1 of my sample data
This is line 2 of my sample data
This is line 3 of my sample data
/*
//SYSUT2   DD DSN=MY.NEW.DATA,DISP=(NEW,CATLG,DELETE),
//            UNIT=SYSDA,SPACE=(TRK,(1,1)),
//            DCB=(RECFM=FB,LRECL=80,BLKSIZE=27920)
//SYSIN    DD DUMMY

Control Statements

For more advanced operations, IEBGENER accepts control statements in the SYSIN dataset. These statements allow you to perform more complex manipulations of your data.

Main Control Statements

Statement	Purpose
GENERATE	Specifies processing options for the entire operation
RECORD	Defines record manipulations (field editing, positioning)
LABELS	Handles label processing for tape datasets
MEMBER	Used when processing members of partitioned datasets

Using the GENERATE Statement

The GENERATE statement specifies general processing options:

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//CTRLSTMT EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1   DD DSN=INPUT.DATASET,DISP=SHR
//SYSUT2   DD DSN=OUTPUT.DATASET,DISP=(NEW,CATLG,DELETE),
//            UNIT=SYSDA,SPACE=(TRK,(5,2))
//SYSIN    DD *
  GENERATE MAXFLDS=5,MAXLITS=100
/*

This example specifies that up to 5 fields and 100 literals will be used in the operation.

Record Manipulation with the RECORD Statement

The RECORD statement allows field-level manipulation:

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//EDITRECS EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1   DD DSN=INPUT.DATASET,DISP=SHR
//SYSUT2   DD DSN=OUTPUT.DATASET,DISP=(NEW,CATLG,DELETE),
//            UNIT=SYSDA,SPACE=(TRK,(5,2)),
//            DCB=(RECFM=FB,LRECL=80,BLKSIZE=27920)
//SYSIN    DD *
  GENERATE MAXFLDS=3
  RECORD FIELD=(10,1,1),FIELD=(15,11,50),FIELD=(5,26,'FIXED')
/*

This example creates records with three fields: 10 bytes from position 1 of the input, 15 bytes from position 11, and a literal 'FIXED'.

Control Statement Format Tips:

Control statements must start in column 2 or beyond
Statements can be continued by ending a line with a comma and continuing on the next line
Comment statements can be included by placing an asterisk (*) in column 1
IEBGENER is sensitive to statement syntax - check documentation for exact formats

Adding or Modifying Records

IEBGENER can also be used to add new records to a dataset or modify existing ones.

Adding a Header and Footer

To add header and footer records to a dataset:

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//ADDRECS  EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//HEADER   DD *
***** REPORT HEADER *****
/*
//CONTENT  DD DSN=REPORT.DATA,DISP=SHR
//FOOTER   DD *
***** END OF REPORT *****
/*
//SYSUT1   DD DSN=&&COMBINED,DISP=(NEW,PASS),
//            UNIT=SYSDA,SPACE=(TRK,(1,1)),
//            DCB=(RECFM=FB,LRECL=80,BLKSIZE=27920)
//         DD DSN=*.HEADER
//         DD DSN=*.CONTENT
//         DD DSN=*.FOOTER
//SYSUT2   DD DSN=FINAL.REPORT,DISP=(NEW,CATLG,DELETE),
//            UNIT=SYSDA,SPACE=(TRK,(5,2)),
//            DCB=(RECFM=FB,LRECL=80,BLKSIZE=27920)
//SYSIN    DD DUMMY

This example concatenates header records, content records, and footer records to create a complete report.

Inserting Records at Specific Positions

To insert records at specific positions using control statements:

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//INSERT   EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1   DD DSN=ORIGINAL.DATA,DISP=SHR
//SYSUT2   DD DSN=MODIFIED.DATA,DISP=(NEW,CATLG,DELETE),
//            UNIT=SYSDA,SPACE=(TRK,(5,2)),
//            DCB=(RECFM=FB,LRECL=80,BLKSIZE=27920)
//SYSIN    DD *
  GENERATE MAXLITS=80
  RECORD IDENT=(8,'SECTION1',1),FIELD=(80,'NEW RECORD FOR SECTION 1')
  RECORD IDENT=(8,'SECTION2',1),FIELD=(80,'NEW RECORD FOR SECTION 2')
/*

This example inserts new records after records that contain 'SECTION1' or 'SECTION2' in the first 8 positions.

Practical Examples

Let's look at some common real-world use cases for IEBGENER.

Example 1: Creating a Report from Raw Data

This example formats raw data into a printable report:

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//REPORT   EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1   DD DSN=SALES.DATA,DISP=SHR
//SYSUT2   DD SYSOUT=A,
//            DCB=(RECFM=FBA,LRECL=133,BLKSIZE=1330)
//SYSIN    DD *
  GENERATE MAXFLDS=5,MAXLITS=100
  RECORD FIELD=(1,1,10),FIELD=(20,11,'SALES REPORT FOR: '),
         FIELD=(10,31,20)
/*

This creates a formatted report directed to the printer, with custom field placements and headers.

Example 2: Converting Legacy Data Format

Converting an old variable-length dataset to fixed format for modern applications:

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//CONVERT  EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1   DD DSN=LEGACY.VB.DATA,DISP=SHR
//SYSUT2   DD DSN=MODERN.FB.DATA,DISP=(NEW,CATLG,DELETE),
//            UNIT=SYSDA,SPACE=(CYL,(1,1)),
//            DCB=(RECFM=FB,LRECL=100,BLKSIZE=27900)
//SYSIN    DD *
  GENERATE MAXFLDS=3
  RECORD FIELD=(1,1,4,HE),FIELD=(8,5,8),FIELD=(87,13)
/*

This example converts data and also rearranges fields to match a new record layout.

Example 3: Simple Backup Copy

Creating a backup copy of a critical dataset:

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//BACKUP   EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1   DD DSN=CRITICAL.MASTER.FILE,DISP=SHR
//SYSUT2   DD DSN=CRITICAL.MASTER.BACKUP.D&&YYMMDD,
//            DISP=(NEW,CATLG,DELETE),
//            UNIT=SYSDA,SPACE=(CYL,(10,5),RLSE),
//            DCB=(*.SYSUT1)
//SYSIN    DD DUMMY

This example creates a date-stamped backup, using the DCB attributes of the input dataset.

Best Practices and Common Mistakes

While IEBGENER is a straightforward utility, there are several best practices to follow and common mistakes to avoid.

Best Practices

Use DCB=(*.SYSUT1) to preserve input dataset characteristics when appropriate
Specify sufficient space for the output dataset
Use DUMMY for SYSIN when no control statements are needed
Always check return codes in production jobs
Consider using more modern utilities like DFSORT for complex operations

Common Mistakes

Not providing enough space for the output dataset
Forgetting to specify DCB parameters when needed
Using incorrect control statement syntax
Trying to use IEBGENER for complex manipulations better suited to other utilities
Not checking for truncation when converting between record formats

When to Use Alternatives

While IEBGENER is versatile, there are cases where other utilities might be more appropriate:

Scenario	Recommended Utility
Copying VSAM datasets	IDCAMS REPRO
Complex data manipulations	DFSORT, ICETOOL
Copying partitioned datasets	IEBCOPY
Sophisticated report formatting	Custom programs, DFSORT ICETOOL

Common Questions and Issues

Test Your Knowledge

1. What is the primary purpose of the IEBGENER utility?

To sort datasets
To copy and convert datasets
To compress partitioned datasets
To catalog datasets

2. Which DD statement is used for input in IEBGENER?

SYSUT1
SYSIN
INPUT
SORTIN

3. Which DD statement is used for output in IEBGENER?

SYSUT2
SYSOUT
OUTPUT
SORTOUT

4. What statement would you use to change record format during a copy operation in IEBGENER?

RECFM=FB
DCB=(RECFM=FB,...)
CONVERT=FB
FORMAT=FB

5. Which of these is NOT a valid function of IEBGENER?

Copy sequential dataset
Convert record formats
Reblock records
Index a VSAM dataset

6. When copying a dataset with IEBGENER, how would you specify the block size for the output dataset?

BLKSIZE=32760
DCB=(BLKSIZE=32760)
BLOCK=32760
SIZE=32760

Restart and Recovery IEBCOPY Utility