The following is an example of how two workstations are allocated to two different subsystems.
In this scenario, subsystem A and subsystem B have workstations DSP01 and DSP02 in their subsystem descriptions (the workstation entries specify AT(*SIGNON)).
| Device Name | Allocated to |
|---|---|
| DSP01 | Subsystem A |
| DSP02 | Subsystem A |
Assume that both workstations are varied on when subsystem A is started.
Subsystem A allocates both workstations and shows the signon display on both. Even though subsystem A has the signon display shown on the workstations, they can be allocated by another subsystem or job; the workstation will then no longer be available to subsystem A.
| Device Name | Allocated to |
|---|---|
| DSP01 | USER1 |
| DSP02 | Subsystem A |
When a user (USER1) signs on to workstation DSP01, the device is allocated to USER1's job, which is running in subsystem A. Workstation DSP02 is still at the signon display. Thus it can be allocated by another subsystem or job. It is then no longer available to subsystem A.
| Device Name | Allocated to |
|---|---|
| DSP01 | USER1 |
| DSP02 | Subsystem B |
Subsystem B is started. Because USER1 has signed on to workstation DSP01, subsystem B cannot allocate the device. Subsystem B requests allocation of the device when it becomes available. DSP02 is allocated to subsystem B because no one has signed on to it in subsystem A. Any jobs started on DSP02 will run in subsystem B.
| Device Name | Allocated to |
|---|---|
| DSP01 | Subsystem A |
| DSP02 | Subsystem B |
USER1 signs off. Because the user job was running in subsystem A, that subsystem displays the signon display so that another user can sign on the workstation and run in subsystem A. If subsystem A is ended, workstation DSP01 is allocated by subsystem B (because it has an outstanding request to allocate the device.)
The name of the subsystem that currently has a workstation allocated appears in the upper right corner of the IBM-supplied signon display.