The following sequence of steps establishes the environment for implementing unattended operations with cartridge loaders:

1. Set the Mode Selection switch on the cartridge loader to system mode. System mode enables the cartridge loader to function differently for specific and nonspecific tape-mount requests. System mode also causes the cartridge loader to wait for scratch tape mounts before it inserts a cartridge into the drive.
2. The global scratch pool optimizes unattended operation. Ensure that you have specified the following commands in your ARCCMDxx PARMLIB member to fully utilize cartridge loaders:
   • SETSYS SELECTVOLUME (SCRATCH)
   • SETSYS PARTIALTAPE(MARKFULL)
   • SETSYS TAPEDELETION(SCRATCH)
   Table 1 describes the result of each of these SETSYS commands.

   Table 1. Defining the Cartridge-Loader Environment

   SETSYS Command	Result
   SETSYS SELECTVOLUME    (SCRATCH)	Creates a tape processing environment that enables most DFSMShsm output tapes to be scratch and hence enables unattended-output operation. By doing so, you direct DFSMShsm to issue nonspecific volume (PRIVAT) mount requests when it encounters an end-of-volume condition during tape output processing. The mount PRIVAT request causes the cartridge loader to mount the next cartridge automatically. For more information about defining scratch pools, see Selecting a scratch pool environment.
   SETSYS PARTIALTAPE    (MARKFULL)	Directs DFSMShsm to mark partially filled tapes full. Even though there may be additional room on the tape, by marking the tape full, DFSMShsm enables a scratch tape to be selected for the initial tape the next time the same function begins. The MARKFULL option enables the system to be unattended at the time the function begins; the REUSE option requires an operator to be present to mount the initial tape for each task of the function, therefore, enabling unattended operation only after the initial tape for each task has been mounted. For more information about marking tapes full, see Selecting a scratch pool environment.
   SETSYS TAPEDELETION    (SCRATCHTAPE)	Directs DFSMShsm to release recycled tapes to the global scratch pool and delete its records of them. For more information about returning empty tapes to the scratch pool, see Selecting a scratch pool environment.

3. Ensure that tape devices with cartridge loaders are allocated for DFSMShsm tape requests.

   You should define esoteric unit names to restrict certain tape devices to DFSMShsm’s use, at least for the time that the DFSMShsm function runs. You could use different esoteric unit names for different DFSMShsm functions. If only some of your cartridge-type tape devices have cartridge loaders, define an esoteric unit name to MVS™ so that there is a device name that can restrict a DFSMShsm function to selecting only tape devices that have cartridge loaders.

   If you have defined an esoteric unit name for 3480 or 3490 devices that have cartridge loaders and if you specify the esoteric unit name in the unittype subparameter, DFSMShsm requests output scratch tape mounts only for the esoteric unit name, and MVS allocates only devices that have the cartridge loader installed. (For more information about esoteric unit names, see the USERUNITTABLE parameter of the SETSYS command in z/OS DFSMShsm Storage Administration.) For more information about defining esoteric unit names, see Restricting tape device selection.

4. Ensure that empty tapes can be returned to scratch status.

   If you are using a tape management system other than DFSMSrmm, ensure that you have specified SETSYS EXITON(TV) to invoke the tape volume exit so that tapes can be returned to the global scratch pool. For more information about coordinating DFSMShsm and a tape management system, see Communicating with the tape management system.

   If you are not using a tape management system, ensure that you have specified SETSYS TAPESECURITY(RACF|RACFINCLUDE) to make tapes immediately usable when they are automatically returned to the scratch pool. For more information about removing protection from empty tapes, see Removing the security on tapes returning to the scratch pool.

5. Do not make any volumes known to DFSMShsm with the ADDVOL command. The operator then can load scratch tapes into all of the tape devices that DFSMShsm selects and can leave the tape devices unattended while DFSMShsm performs its output functions.