Creating a Subsystem
Description
You can create a subsystem description
in two ways. You can copy an existing
subsystem description and change it, or
you can create an entirely new description.
The following are two approaches you
can use:
v Copying an existing
subsystem description
1. Create a duplicate object,
CRTDUPOBJ, of an existing subsystem
description. (You can also use the
WRKOBJ or WRKOBJPDM commands.)
2. Change the copy of the subsystem
description.
See Appendix C. IBM-Supplied Object
Contents, for examples.
v Creating an entirely
new subsystem description
1. Create a subsystem description
(CRTSBSD).
2. Create a job description (CRTJOBD).
3. Add work entries to the subsystem
description.
a. ADDWSE (Add workstation entry)
b. ADDJOBQE (Add job queue entry)
c. ADDCMNE (Add communications entry)
d. ADDAJE (Add autostart job entry)
e. ADDPJE (Add prestart job entry)
4. Create a class (CRTCLS).
5. Add routing entries to the
subsystem description (ADDRTGE).
Starting a Subsystem
To start a subsystem, use the Start
Subsystem (STRSBS) command or the Work
with Subsystem Description (WRKSBSD)
command. To use the STRSBS
command, specify the following:
STRSBS SBSD
(SBSD=library/subsystem
description name)
For example
STRSBS
MYLIB/MYSTORE
How a Subsystem
Starts
When a subsystem starts, the system
allocates several items and starts autostart
and prestart jobs before it is ready
for work.
1. After the Start Subsystem (STRSBS)
command is issued, the system allocates
the following items, finding the
information in the subsystem description:
v Pools of main storage
v Display stations
v Communications
devices
v Job queues
2. Next, the autostart jobs and
prestart jobs are started and the subsystem is
ready for work. Figure 3 shows what
occurs when a subsystem starts.
Chapter 4. Subsystems 83
Subsystem Monitor Job
The subsystem monitor job provides
control over an active subsystem. It provides
functions such as initiating,
controlling, and ending jobs. Several subsystem monitor
jobs may run on a system at any given
time.
Subsystem monitor jobs are identified
by type SBS on the Work with Active Jobs
display. You can see this by using the
Work with Active Jobs (WRKACTJOB)
command.
Note: IBM supplies two
complete controlling subsystem configurations: QBASE
(the default controlling subsystem),
and QCTL. Only one controlling
subsystem can be active on the system
at one time. The Controlling
Subsystem Description (QCTLSBSD) system value determines
