//SMSDS3  DD  DSNAME=MYDS3.PGM,DATACLAS=VSAM1,DISP=(NEW,KEEP),
//          KEYOFF=2

In the example, the data class VSAM1 defines a key-sequenced VSAM data set. The key offset of 2 overrides the key offset defined in the data class and specifies that the first byte of the key is in the third position of each record.