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Allocating New Disk Datasets

In an SMS (System Managed Storage) environment, some additional facilities are available to simplify the JCL for allocating new datasets. For example, the AVGREC parameter allows you to specify the size of a new dataset in terms of the number of records. For example, //NEW DD DISP=(,CATLG,DELETE),,UNIT=SYSDA, // AVGREC=U,SPACE=(80,(100,50),RLSE),RECFM=FB,LRECL=80 specifies that the primary size for the dataset is 100 records of size 80 bytes with a space increment of 50 records. For variable length records (RECFM=VB), LRECL would be the maximum record length and the first subparameter for the SPACE parameter would be the average record length.

You can also specify:

Cloning an Existing Dataset

The LIKE parameter can be used to copy space and DCB attributes from an existing dataset. For example, //COPY EXEC SORT //SORTIN DD DISP=SHR,DSN=input.dataset //SORTOUT DD DISP=(,CATLG,DELETE),DSN=output.dataset, // LIKE=input.dataset //SYSIN DD * SORT FIELDS=COPY could be used to create a second copy of an existing dataset.


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