Allocation of direct access space

You must request space for every non-VSAM or non-SMS-managed data set being created on a direct access volume. To tell the system how much space is needed and let the system assign the tracks, code:

//ddname  DD  SPACE=(TRK,(primary-qty,second-qty,directory or index)),...
//ddname  DD  SPACE=(CYL,(primary-qty,second-qty,directory or index)),...
//ddname  DD  SPACE=(blklgth,(primary-qty,second-qty,directory or index)),...

To tell the system the specific tracks to assign to the data set, code:

//ddname  DD  SPACE=(ABSTR,(primary-qty,address,directory or index)),...

With SMS, you can request space or override the space allocation defined in the data class for the data set. In this case, code:

//ddname  DD  SPACE=(reclgth,(primary-qty,second-qty,directory)),
            AVGREC=value,...  

Also with SMS, you can code the DATACLAS parameter (or let an ACS routine select a data class) to specify space allocation, for example:

   //ddname  DD  DATACLAS=dataclass-name,...