Using dynamic allocation for tape drives

OAM uses the z/OS dynamic allocation macro (DYNALLOC) for all tape drive allocations. Tape drives remain allocated while OAM is using them, but are then dynamically deallocated when OAM no longer needs them. Thus, the tape drives are obtained and released as OAM needs them; the tape drives are not dedicated to OAM. The tape drives are allocated to the OAM address space and not the application address space (for example, CICS, IMS MPP, or IMS BMP) invoking the OAM application programming interface (the OSREQ macro).

The allocated device could be a stand-alone tape drive or a drive inside of an automated or manual tape library. The device allocation depends on:

The contents of the ACS routines
Whether this mount is for an existing OAM tape that contains objects or a mount for an MVS scratch tape
The location of the volume to be mounted

Although tape drives are not permanently allocated to the OAM address space, tape drives must be available to the OAM address space when they are needed to handle a request to store or retrieve an object on a tape volume.

The maximum number of tape drives capable of being concurrently allocated to the OAM address space is controlled by the sum of the MAXTAPESTORETASKS and the MAXTAPERETRIEVETASKS keywords at the OAM global level on the SETOAM statement.