CL Programming
All messages on the system are sent to a message queue. The system
user or program associated with the message queue receives the message from
the queue. Similarly, a reply to a message is sent back to the message
queue of the user or program requesting the reply.
The following diagrams show the message queues supplied by IBM. A
message queue is supplied for each display station (where DSP01 and DSP02 are
display station names) and each user profile (where BOB and RAY are user
profile names):

Job message queues are supplied for each job running on the system.
Each job is given an external message queue (*EXT) and each call of an OPM
program or ILE procedure within the job has its own call message queue.

Message queues are also supplied for the system history log (QHST) and the
system operator (QSYSOPR):

These message queues are used as follows:
- Work station message queues are used for sending and receiving messages
between work station users and between work station users and the system
operator. The name of the queue is the same as the name of the work
station. The queue is created by the system when the work station is
described to the system.
- User profile message queues can be used for communication between
users. User profile message queues are automatically created in library
QUSRSYS when the user profile is created.
-
Job message queues are used for receiving requests to be processed (such as
commands) and for sending messages that result from processing the
requests; the messages are sent to the requester of the job. Job
message queues exist for each job and only exist for the life of the
job. Job message queues consist of an external message queue (*EXT) and
a set of call stack entry message queues. See Job Message Queues for more information.
- System operator message queue (QSYSOPR) is used for receiving and replying
to messages from the system, display station users, and application
programs.
- The history log message queue is used for sending information to the
history log (QHST) from any job in the system.
In addition to these message queues, you can create your own user message
queues for sending messages to system users and between application
programs.
[ Top of Page | Previous Page | Next Page | Table of Contents | Index ]
(C) Copyright IBM Corporation 1992, 2005. All Rights Reserved.