Assign a permanent DSN to every SORTWKxx DD statement and specify the UNIT, SPACE and VOL=SER parameters in case a deferred restart becomes necessary. Avoid using passed data sets, JCL refer-backs, and any other references which would make the JCL following the restart dependent on the JCL preceding the restart.
Note that the SORTCKPT data set and the SORTWKxx data set(s) may reside on the
same direct access device without loss of efficiency.
Figure 1. Sample SORTCKPT DD Statement