//SORTCKPT DD  DSNAME=CHECK,VOLUME=SER=000123,
//             DSP=(NEW,KEEP),UNIT=3480

When you allocate the SORTCKPT data set, you must include at least one work data set.

If the CKPT operand is specified on the OPTION or SORT control statement, more intermediate storage could be required.

If you want to use the Checkpoint/Restart Facility, refer to Checkpoint/restart.