A simple method of performing IPC within a single job or session is the use of variables and Job Control Words (JCWs). This feature is described in Chapter 2.
The file system intrinsics provide the most powerful method of performing IPC. These intrinsics can be used to communicate between a process and any other process; the processes need not be part of the same process tree or running in the same job or session. Communication takes place through the use of message files. Chapters 3-6 discuss the file system intrinsics used to perform IPC and give examples of how to set up communications between processes.
Some systems use the MAIL facility to communicate between processes in the same process tree. Each process in the tree can use this facility to send information to a parent or child process. The MAIL facility is covered in Chapter 7 of this manual.
