DD Referbacks  (text pg 84, 111-112, 122, 143)

A JCL Referback can be used to:

  • To keep related files on the same volume without repeatedly coding the same VOL=SER.

  • To use the DCB information from an existing dataset for a new version of that dataset without knowing that information.

  • Reduce redundant information in a JCL stream, and thus to reduce maintenance costs.

VOL=REF

The VOL subparameter REF is used to direct a DD statement to the volume used by another dataset:

    // VOL=REF=dsn,

e.g. In the following, the new dataset will be created on the same volume as the old one.

    //OUTPUT DD DSN=AHSA.VERS2,DISP=(NEW,CATLG),
    // VOL=REF=AHSA.VERS1

Another form of VOL=REF is used to direct a dataset to the volume used by another DD stmt, by providing the name of the DD statement and the step and, optionally, of the proc step containing that DD statement:

    // VOL=REF=*.step[.procstep].ddname,

e.g. In the following example, the file OUTPUT will be written to the same volume used by the dataset pointed to by the DD name INPUT:

    //OUTPUT DD DSN=AHSA.VERS2,DISP=(NEW,CATLG),VOL=REF=*.INPUT

Here step and procstep have been omitted, indicating that INPUT is a DD statement in the same step as OUTPUT.

DCB Referbacks

A referback can also be used as the value of the DCB parameter, to direct that a (new) dataset be assigned the same DCB attributes of an existing dataset.

e.g In the the following, the file OUTPUT is defined to have the same DCB information as the file INPUT:

    //OUTPUT DD DCB=*.INPUT,...

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