CHKPT control statement

You can use the CHKPT control statement to specify options for the Automatic Restart feature.

Use of this control statement is optional if you specify a DD statement to define the checkpoint data set. Use the following syntax:

Related topics

Using-the-Automatic-Restart-feature

CHKPT  RESTART(value)  DDN(value)  CHKPTRPT(value)

The keywords from the following table are valid on the CHKPT control statement.

Keyword

Description

RESTART(value)

The RESTART keyword specifies the restart mode. The following values are valid:

  • A or AUTO—The utility reads the checkpoint data set to determine whether a warm start (restart) or cold start is needed. This value is the default, and you typically would use it for completely automated restart.
  • Y—The utility ensures that the job step is restarted. If the checkpoint data set is not flagged for restart, the utility terminates the job step. This value provides a safety mechanism that you can use to make sure that a restart is performed.
  • N—A cold start is forced. The utility does not perform a restart even if the checkpoint data set indicates a 'restart needed' condition. If Snapshot resources are still tied up (mirrors are split or cache preimages are being held), the utility frees them before starting the job step.

CHKPTRPT(value)

The CHKPT keyword controls the production of a report that shows the status of each entry (a database and data set group, partition, or area) in the checkpoint data set. The following values are valid:

  • N—The utility does not generate the report. This value is the default.
  • Y—The utility generates the report at the end of execution of the utility job step. If the DETAIL DD statement is allocated in the JCL, the report is written to the DETAIL data set. If a DETAIL DD statement is not allocated in the JCL but a REPORTS DD statement is allocated, the report is written to the REPORTS data set. If neither statement is allocated, the report is written to the SYSPRINT data set.
  • O—The utility generates the Checkpoint Status Report only and does not perform any image copy or database recovery. It writes the report to the SYSPRINT data set.

DDN(value)

The DDN keyword identifies the checkpoint data set. Specify either of the following values:

  • Specify the ddname of the DD statement for the checkpoint data set in the job step JCL. The default ddname is ICPCHKPT.
  • Specify (*,modelname) to allocate the checkpoint data set by using the indicated dynamic allocation model.

If you specify a dynamic allocation model, the utility builds the checkpoint data set by using the model definitions and substituting appropriate values for any substitution variables. If the checkpoint data set does not already exist, the utility allocates it dynamically and performs a cold-start. If the data set already exists, the utility allocates it dynamically, validates the data set attributes, and proceeds through the normal logic of determining whether to perform a cold-start or restart.

The checkpoint data set name must remain unchanged from one execution to the next. You cannot specify a data set name prefix in the model. You can use the following set of substitution variables when you specify the data set name with a model:

  • &JOB
  • &STEP
  • &PROC
  • &IMSID
  • &TYPE

 

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