MARENUCP is a permanent batch task running under a user ID which has been configured with the TAPE-ADMINISTRATION privilege and the operator role which is entered in the system-specific MAREN parameters. MARENUCP establishes a connection to UCON. No authorization name is required for connection setup. It reads all messages referring to tape processing through the UCON interface.
A request for an free tape triggers the following steps in MARENUCP:
- Determination of the tapes mounted on the devices.
- A mounted, free tape is determined and reserved in the MAREN catalog. A reservation file or a MAREN exit is taken into consideration here.
- If no free mounted tape is found, then the operator is requested to mount one. It is not necessary to respond to the prompt, because MARENUCP will detect when the tape is mounted.
VSN proposal
In the event of a corresponding request, MARENUCP requests the operator to mount a free tape: MOUNT TAPE <vsn>,...
The operator can mount the proposed tape or a different free tape, which is then automatically allocated. If a free tape is already mounted, this is allocated without a request being issued to the operator.
The sequence in which tapes are proposed is defined automatically on the basis of how frequently they are utilized. Tapes that are used less frequently are proposed first.
The criterion used to measure the frequency with which a volume is used is defined with the system-specific MAREN parameter RESERVATION-SEQUENCE. The possible selection criteria are VSN, RESERVATION-COUNT, LAST-ACCESS-DATE and FREE-DATE.