Data classes help you migrate generation data sets to the system-managed environment. They represent one way of replacing the unsupported pattern DSCBs. One class, GDGV104, is defined for data sets having variable length records and another class, GDGF80, supports data sets with fixed length records. An average primary space allocation of 800 KB is requested for data sets assigned the GDGF80 data class, and 520 MB is requested for GDGV104. As with other data classes, the user can supply other DCB parameters to supplement or override the ones in the assigned data class. The attributes for GDGF80 and GDGV104 are listed in Table 1.

Users can assign the data classes created to replace the GDG pattern DSCBs by specifying the data class, using the DATACLAS parameter on the DD statement for the GDS. Or, you can automate assignment of data classes by testing the &DSTYPE variable for the value GDS and the data set name.