How tasks are made to wait

The suspension and resumption of tasks in a CICS® system are performed by the dispatcher domain, usually on behalf of some other CICS component. If the exit programming interface (XPI) is being used, it can be at the request of user code.

The major dispatcher functions associated with the suspension and subsequent resumption of tasks are described in detail in Dispatcher domain (DS). You can use trace to see the dispatcher functions that are requested, and the values of parameters that are supplied. See Investigating waits using trace .

Some of the dispatcher functions are available to users through the exit programming interface (XPI). If you have any applications using these XPI functions, make sure that they follow the rules and protocols exactly. For programming information about the XPI, see XPI functions (by domain).

If you want guidance about using online or offline techniques to investigate waits, see Techniques for investigating waits.

If you already know the identity of the resource that a task is waiting for, but are not sure what functional area of CICS is involved, see Table 1. It shows you where to look for further guidance.

Throughout this section, the terms “suspension” and “resumption” and “suspended” and “resumed” are used generically. Except where otherwise indicated, they refer to any of the SUSPEND/RESUME and WAIT/POST processes by which tasks can be made to stop running and then be made ready to run again.

This section covers information on the following waits: