The IATXRABC macro allocates track groups to create a record allocation block (RAB).

The issuing routine must specify the number of track groups to be allocated in field RABTRKG1 of the RAB specified by the RAB parameter. The IATXRABC macro returns the number of track groups actually allocated in field RABTRKG2 of the RAB.

If no track groups are available in the spool partition identified by the job or data set TAT (specified indirectly using the FDB parameter), the IATXRABC service routine issues an AWAIT TYPE=OFF macro to wait until track groups become available. The service routine also issues an AWAIT TYPE=OFF macro if a minimal spool space condition exists for the identified spool partition. If enough track groups are available in the spool partition to obtain at least one, but not all, of the requested track groups, those track groups that were obtained will be returned to the caller.