How workstation devices are allocated
Subsystems attempt to allocate all workstation devices in its subsystem description for AT(*SIGNON) workstation entries.
The following situations might occur during the time the subsystem starts:
- If the device is not varied on, the subsystem cannot allocate it. The system arbiter (QSYSARB) and the QCMNARBxx jobs hold locks on all varied-off devices.
- If the device is varied on and has not been allocated by any other subsystem, the subsystem can allocate it and display the signon display.
- If the device is varied on and has been allocated by another subsystem and is at the signon display (the signon display was displayed before the second subsystem was started), a second subsystem can allocate the device from the first subsystem and display the signon display.
If more than one subsystem tries to allocate the same workstation (as specified in the workstation entries) and the workstation is varied off, the subsystem that gets the workstation when it is varied on cannot be predicted. Similarly, if a workstation entry specifies a workstation type instead of a workstation name, a subsystem might get all, some, or none of the workstations of that type. (This also applies to workstation entries with generic names.) To avoid such a situation, you can set up the workstation entries for the subsystems so multiple subsystems are not using the same workstations.
After a user has signed on
When a user signs on to a workstation, the job runs in the subsystem that was shown on the signon display on the workstation (the subsystem is identified in the IBM-supplied signon display). The following situations might occur after the user has signed on:
- If a second subsystem is started and it tries to allocate the workstation on which the user signed on, the second subsystem cannot allocate it. The user’s job continues to run in the first subsystem.
- If the user selects option 1 (Display signon for alternative job) on the System Request menu or issues the Transfer to Secondary Job (TFRSECJOB) command, the new job runs in the same subsystem as the original job.
- When the user signs off, the workstation remains allocated to the subsystem used when the user signed on, unless the user transferred into the subsystem using the Transfer Job (TFRJOB) command, and specified AT (*ENTER) for the workstation entry for this workstation. A signon display is shown, and any subsequent jobs from that workstation continue to run in that subsystem, (unless another subsystem is started up that allocates the workstation while it is at the signon display).
- If the user signs off and the subsystem in which his job was running is ended, the device is deallocated. A second subsystem can then allocate the device and display the signon display.
Parent topic:
How a subsystem startsRelated tasks
Assigning users to a specific subsystem