How a subsystem starts?

When a subsystem starts, the system allocates several items and starts autostart and prestart jobs before the subsystem is ready for work. The subsystem description is used to determine how items are allocated. The following list represents the sequence of events that occur when the subsystem starts:

1. Request to start subsystem is issued.
2. Memory pools are allocated.
3. Prestart jobs are started.
4. Autostart jobs are started.
5. Display stations are allocated (signon displays are up).
6. Job queues are allocated.
7. Communications devices are allocated.
8. The Environment is ready for work.