The SQTY subroutine provides a default secondary space quantity if none is specified. The default is one-half of the primary space quantity if it is greater than one. If the primary quantity is zero, the secondary is set to a fixed default number of tracks (5 in the example). If the primary quantity is one, the secondary is set to the same fixed default (5); the secondary quantity shown is in units of tracks, cylinders, or average blocks, depending on the unit of the primary quantity.

If the secondary space quantity is not zero, the SQTY subroutine tests the number of extents in the data set. If the number of extents is equal to, or greater than, a fixed value (10 in the example), then the secondary quantity is increased by 50% if it is greater than 1. It is set to a default quantity (5 in the example) if the secondary quantity is one; thesecondary quantity shown is in units of tracks, cylinders, or average blocks, depending on that of the primary quantity.

You can provide space defaults more efficiently by using data classes. This allows greater selectivity according to the type of data set. To use data classes, SMS must be running, but the data set does not have to be SMS-managed.