Restrictions

If the access method services job step contains either the SYSTSIN or SYSTSPRT DD statements, the ALLOCATE command is unsuccessful. Access method services allocates the SYSTSIN and SYSTSPRT DD statements to pass the command to the TMP and to retrieve any error messages that are issued. This is done for every ALLOCATE command. Any TMP error messages appear in the SYSPRINT data set, and access method services prints a summary message to show the final status of the command.
The access method services ALLOCATE command is not supported if access method services is called in the foreground of TSO or if Time Sharing Option Extensions (TSO/E) Release 2 or later is not installed.
You cannot use ALLOCATE if you have used the ATTACH macro to call IDCAMS from an application program. If you do, ALLOCATE fails with an ATTACH return code.