Thursday, September 6, 2012

Subsystem Details:


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