General Information for PREVENT-NCT2

If a job tries to create a data set that already exists, the job may fail with a DUPLICATE DATASET ON VOLUME error. If a job tries to create a data set whose name is already cataloged, the job may fail with an error message that indicates a reason of NOT CATLGD for reason code 2; the Control-M/Restart term PREVENT-NCT2 is derived from this error situation.

These problems can be avoided by performing data set cleanup. During data set cleanup, Control-M/Restart does the following:

• Deletes and uncatalogs the old data sets. This prevents DUPLICATE DATSET ON VOLUME and NOT CATLGD 2 errors.
• Performs Generation Dataset (GDG) Adjustment, which is described in the Control-M/Restart User Guide

Control-M/Restart automatically performs data set cleanup prior to restarts and reruns. However, it may be desirable to perform data set cleanup before the original job run, because data sets accessed by the job can have file-related errors that were generated by an entirely different job.

When data set cleanup is performed as part of the original job request, it is called PREVENT-NCT2 processing.

The site-defined default in NCAT2 in the CTRPARM member determines whether data set cleanup is to be performed before the original job run. The value of this site-defined default is displayed in protected field DFLT.

The PREVENT-NCT2 parameter can be used to override this default to determine what data set cleanup instructions are provided to the original job run. Possible values, and their effects, are described below:

• When value Y is specified:

  Control-M/Restart performs data set cleanup before the original job run. It deletes and uncatalogs all data sets that can cause NCT2 and duplicate data set errors during execution, and performs GDG adjustment if necessary.

• When value F is specified:

  If a file catalog error is detected, processing is halted, even if normal MVS processing would not handle the problems as a fatal error, and an appropriate error message is generated.

• When value L is specified:

  Data set cleanup is not performed for the original run, but messages that would be required for GDG adjustment during restart are generated. Without these messages, GDG adjustment might not be properly performed during restart. In addition to the GDG adjustment messages, the same messages that are generated during simulation of data set cleanup are also generated.

Note: If you would normally specify N, meaning Control-M/Restart processing is not desired for the original run, but the JCL requires GDG processing, it is recommended that you specify value L instead of value N.

• When value N is specified:

  No special action is taken by Control-M/Restart. Data set cleanup is not performed.

If a value of Y, F, or L is specified, that is, if some kind of special NCT2 processing is desired, a CONTROLR step is automatically added as a first step of the submitted job.

The PREVENT NCT2 parameter has no impact on restarts, because Control-M/Restart automatically performs data set cleanup prior to restarts.

Note: When PREVENT-NCT2 is active for a job, it is possible to automatically collect certain statistical information on the job. For more details, see the AUTOXREF parameter in the INCONTROL for z/OS Installation Guide: Customizing.

Note: To globally disable the Prevent-NCT2 processing, which will force Control-M to consider not-catalogued errors as OK, customize and apply the CTMSNCT member in the IOA SAMPEXIT library.