MAREN must define a location when the following conditions are met:
more than one location is being operated with tape processing in a data center (i.e. especially if manually operated devices are being used as well as an archive system);
there are applications which neither explicitly nor implicitly (by specifying an archive number) specify the location.
MAREN allocates a location for the following applications:
Device reservation by means of the SECURE-RESOURCE-ALLOCATION command without explicit specification of a location.
Device reservation for a scratch request.
Free tape allocation by MAREN for a scratch request.
Location definition without MAREN exits and reservation file
MAREN selects the first archive system entered in the location table. If there is no archive system in the table, MAREN uses the location specified in the system-specific MAREN parameter DEFAULT-HOME-LOC.
If this location assignment does not meet the requirements of the data center, because, for example, there are two tape locations to be used for handling scratch requests, the location definition must be controlled by a reservation file or MAREN exits.
Location definition with a reservation file
The location can be defined with a reservation file (see section “Location management via a reservation file”). The MAREN administrator creates and edits the reservation file using the MARENLM program (see section “Editing the reservation file with MARENLM”) or an editor.
Location definition using MAREN exits
Instead of defining the location via a reservation file or in addition to this, it is also possible to define the location via MAREN exits (see the chapter “MAREN exits”). In the applications (1) and (2) named above, the device depot exit MARENEX6 is used and in the application (3) the reserve request exit MARENEX1 is used.
In both exit routines, the location name can be input either directly or indirectly by specifying a number range.
The decisive criterion for direct or indirect specification of the location name in the exits can be the file name, the volume type, the job name, or the user ID.
When evaluating the volume type, note that MAREN transfers it in different formats to the exits. For example, when a tape of type TAPE-C4 is requested, MAREN transfers the volume type code CL2'BC' to exit MARENEX1 in the 2-byte long DEVICE field and the volume type “TAPE-C4 ” to exit MARENEX6 in the 8-byte long DEVTYPE field (in USERFELD). The volume type codes can be found in the the manual “System Installation” [6].
For scratch requests, the location is determined twice (applications (1) and (2)). If a location is determined in one exit, the same location must also be determined in the other exit.