Creating a Model DSCB

You can create a model DSCB on the volume on which your index resides.

Restriction: You cannot use a model DSCB for system-managed generation data sets.

You can provide initial DCB attributes when you create your model; however, you need not provide any attributes now. Because only the attributes in the data set label are used, allocate the model data set with SPACE=(TRK,0) to conserve direct access space. You can supply initial or overriding attributes creating and cataloging a generation. To create a model DSCB, include the following DD statement in the job step that builds the index or in any other job step that precedes the step in which you create and catalog your generation:

   //name DD DSNAME=datagrpname,DISP=(,KEEP),SPACE=(TRK,(0)),
   //        UNIT=yyyy,VOLUME=SER=xxxxxx,
   //        DCB=(applicable subparameters)

Recommendation: Only one model DSCB is necessary for any number of generations. If you plan to use only one model, do not supply DCB attributes when you create the model. When you subsequently create and catalog a generation, include necessary DCB attributes in the DD statement referring to the generation. In this manner, any number of GDGs can refer to the same model. The catalog and model data set label are always located on a direct access volume, even for a magnetic tape GDG.

In the preceding example, datagrpname is the common name that identifies each generation, and xxxxxx is the serial number of the volume that contains the catalog. If you do not want any DCB subparameters initially, you need not code the DCB parameter.

The model DSCB must reside on the catalog volume. If you move a catalog to a new volume, you also need to move or create a new model DSCB on this new volume. If you split or merge a catalog and the catalog remains on the same volume as the existing model DSCB, you do not have to move or create a new model DSCB.