For an SMS-managed data set (one with a storage class assigned), the system handles the migration and backup of the data set based on the attributes defined in the management class for the data set.
In many cases, the attributes defined in the management class selected by an installation-written automatic class selection (ACS) routine are sufficient for the data sets you create with DD statements.
However, you can specify the name of a management class on the MGMTCLAS parameter for a new SMS-managed data set. (Note that an ACS routine can override the management class that you specify.)
The storage administrator at your installation defines the names of management classes and their attributes. To view a list of management class names and their attributes, use the Interactive Storage Management Facility (ISMF).
Note that you cannot override any of the attributes defined in the management class for the data set.
//DD8 DD DSNAME=DESIGND.PGM,DISP=(NEW,KEEP)
//DD9 DD DSNAME=DESIGNE.PGM,MGMTCLAS=MCLASA,DISP=(NEW,KEEP)