Extending on a volume other than the last

When you code DISP=MOD for a multivolume data set, use the volume count and volume sequence number subparameters of the VOLUME parameter if you want to keep the system from positioning the read/write mechanism after the last record on the last volume. For example:

   //DDEX1  DD  DSNAME=OPER.DATA,DISP=(MOD,KEEP),VOLUME=(,,1,2)

The volume sequence number of 1 specifies that you want to use the first volume, and the volume count of 2 specifies that the data set requires two volumes.