Backward references

A backward reference is a reference to an earlier DD statement in the job or in a cataloged or in-stream procedure called by a job step. A backward reference is in the form *.ddname or *.stepname.ddname or *.stepname.procstepname.ddname. The ddname in the reference is the ddname of the earlier DD statement. If the earlier DD statement contains a DDNAME parameter, the reference is to the ddname in the name field of the earlier statement, not to the ddname in the DDNAME parameter.

The DD statement referenced in a DDNAME parameter cannot refer to a DD statement between the statement containing the DDNAME parameter and itself. For example:

//SHOW   EXEC PGM=ABLE
//DD1    DD   DDNAME=INPUT
//DD2    DD   DSNAME=TEMPSPAC,SPACE=(TRK,1),UNIT=SYSDA
//DD3    DD   DSNAME=INCOPY,VOLUME=REF=*.DD1,
//            DISP=(,KEEP),SPACE=(TRK,(5,2))
//DD4    DD   DSNAME=OUTLIST,DISP=OLD
//DD5    DD   DSNAME=MESSAGE,DISP=OLD,UNIT=3390,VOLUME=SER=333333
//INPUT  DD   DSNAME=NEWLIST,DISP=(OLD,KEEP),VOLUME=SER=333333,
//            UNIT=3390

The DDNAME parameter on DD1 refers to DD statement INPUT. The VOLUME parameter of DD3 specifies a backward reference to DD1, which is the name field ddname.

DD statement INPUT identifies the volume 333333 in its VOLUME=SER=333333 parameter. DD statement INPUT cannot use a backward reference to the VOLUME parameter on DD5 because DD5 is between the referring DD1 and the referenced INPUT.