JESLOG Parameter

Purpose

The JESLOG parameter controls how JES manages job log information for a job. It allows you to specify what system and job log data is recorded and how it is handled during job execution. This parameter helps manage spool space and control job-related diagnostic information.

Syntax

Basic Format

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//jobname JOB parameters,JESLOG=option

Extended Format

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//jobname JOB parameters,JESLOG=(option,interval)

Parameter Values

option

interval

Used only with SPIN option, this value specifies when the job log should be spun. There are two ways to specify the interval:

Usage Examples

Default Behavior

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//TESTJOB JOB (ACCT),'JOHN DOE',CLASS=A,
//         MSGCLASS=X

Without the JESLOG parameter, the default is NOSPIN - job log is not available until job completion.

Basic SPIN Option

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//TESTJOB JOB (ACCT),'JOHN DOE',CLASS=A,
//         MSGCLASS=X,JESLOG=SPIN

Job log is made available at the end of the job.

SPIN with Time Interval

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//LONGJOB JOB (ACCT),'JOHN DOE',CLASS=A,
//         MSGCLASS=X,JESLOG=(SPIN,+01:00)

Job log is made available every hour during execution, allowing monitoring of a long-running job.

SPIN with Line Count

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//CHATTY  JOB (ACCT),'JOHN DOE',CLASS=A,
//         MSGCLASS=X,JESLOG=(SPIN,1000)

Job log is made available after every 1000 lines of output, useful for verbose jobs.

Suppressing Job Log

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//NOLOG   JOB (ACCT),'JOHN DOE',CLASS=A,
//         MSGCLASS=X,JESLOG=SUPPRESS

No JES job log is created, reducing spool space usage (JES2 only).

Job Log Content

The job log typically contains:

• JCL statements as processed by the system
• Allocation and deallocation messages
• Job and step initiation and termination messages
• System and operator messages related to the job
• JES processing messages
• System completion codes and related diagnostic information

Use Cases and Benefits

NOSPIN (Default)

• Use when: Job diagnostics are only needed after completion
• Benefits: Simplifies job log management, single job log file

SPIN

• Use when:
  • Jobs run for extended periods
  • Real-time monitoring is required
  • Troubleshooting ongoing issues
  • Progress tracking is needed
• Benefits:
  • Early access to diagnostic information
  • Ability to view job progress without waiting for completion
  • Detection of issues earlier in the job execution

SUPPRESS

• Use when:
  • Job log information is unnecessary
  • Conserving spool space is a priority
  • Running well-tested production jobs
  • High-volume batch processing
• Benefits:
  • Reduced spool usage
  • Improved performance for high-volume jobs
  • Cleaner output management

Implementation Details

JES2 vs. JES3

System Defaults

If the JESLOG parameter is not specified, JES uses installation-defined defaults. These are typically set in the JES initialization parameters:

• JES2: JOBDEF JOBLOG= parameter in JES2PARM
• JES3: STANDARDS JESMSG= parameter in JES3IN

Retention Considerations

When SPIN is used, each spun job log is treated as a separate output data set, with:

• Same output class as specified in MSGCLASS
• Separate retention period based on installation settings
• Individual disposition control (hold, release, purge)

Performance Considerations

Spool Space Management

• SUPPRESS offers the best spool space efficiency
• NOSPIN creates a single job log, using moderate spool space
• SPIN may create multiple job logs, potentially using more spool space

System Resource Impact

Best Practices

1. For short-running jobs: Use NOSPIN (default) or SUPPRESS
2. For long-running jobs: Use SPIN with an appropriate interval
3. For troubleshooting: Use SPIN with a moderate line count (e.g., 500 lines)
4. For production jobs: Consider SUPPRESS once testing is complete
5. For time-based intervals: Balance between timely information and system overhead
6. For high-volume batch: Use larger intervals or SUPPRESS to reduce spool impact
7. Consider installation standards: Follow site-specific guidelines for JESLOG usage

Troubleshooting

Common Issues

Related Concepts

• JOB Statement - The statement where JESLOG is specified
• MSGCLASS Parameter - Controls the output class for job log
• MSGLEVEL Parameter - Controls the level of detail in job log
• BYTES Parameter - Limits the total byte output for a job