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Ü   Subsystem

·         AS400 system contains several subsystems, each working independently and performing some specific task.

·         The job is assigned to a subsystem according to the type of job e.g. one subsystem may handle all interactive job; other may handle all batch job, some other may handle communication jobs etc.

·         Subsystem may also handle different types of job.

·         Each subsystem has its own runtime attribute that is used by the job to get itself executed under that environment.

Simple IBM supplied Subsystem configuration:

·         QBASE                 Supports Interactive, Batch and communication jobs.

·         QSPL                    Spool subsystem that supports reader/writer jobs.

·         QCTL                    Controlling Subsystem that starts up the system console.

·         QINTER               Supports Interactive jobs.

·         QBATCH             Supports Batch jobs.

·         QCMN                  Supports all communication jobs.

·         QSPL                    Supports reader and writer jobs.



                           Work with System Status                   PJIAKID09

                                                            01/03/13  08:09:49

% CPU used . . . . . . . :         .4    Auxiliary storage:

% DB capability  . . . . :         .0      System ASP . . . . . . :    564.5 G

Elapsed time . . . . . . :   00:00:01      % system ASP used  . . :    76.6939

Jobs in system . . . . . :       7158      Total  . . . . . . . . :    564.5 G

% perm addresses . . . . :       .041      Current unprotect used :     4676 M

% temp addresses . . . . :       .459      Maximum unprotect  . . :     5166 M


Type changes (if allowed), press Enter.


System    Pool    Reserved    Max   -----DB-----  ---Non-DB---

Pool   Size (M)  Size (M)  Active  Fault  Pages  Fault  Pages

1      266.70    121.97   +++++     .0     .0    3.4    3.4

2     1169.36      3.07      76     .0     .0     .0     .0

3       24.95       .00       9     .0     .0     .0     .0

4     1034.97       .00      63     .0     .0    6.8    7.7







F3=Exit   F4=Prompt   F5=Refresh   F9=Retrieve   F10=Restart   F12=Cancel

F19=Extended system status         F24=More keys




System pool: A logical division of main memory for allocation of jobs.

Pool size: Amount of allocated memory to a job.

IBM supplied pools:

·         *Machine: No user jobs in this pool and is related to OS/400.

·         *Interact:   Pool made for interactive jobs.

·         *Spool:  Pool made for printer writers.

·         *Base:  Contains whatever storage is left.  Usually used for Batch and miscellaneous work.


Related command è STRSBS, ENDSBS, WRKSBS


Ü  Procedure to create subsystem

·         We can create our own subsystem to run our interactive/batch jobs.

·         We can start or end the subsystem whenever we need without disrupting our other system jobs that may be running in QINTER/QBATCH.

·         To create our simple batch subsystem, we need below elements:

·         Subsystem description: It describes the working environment of the subsystem e.g. maximum no. of  jobs in the subsystem at a time, storage capability of the subsystem, pool identifier etc.

·         Job queue: From which the jobs will be feed to run in the subsystem.

·         Class object: It describes the runtime attributes of jobs entering this subsystem.

·         Routing entries: It tells the subsystem how to process incoming requests.



Ü Steps of creating the subsystem


ü  Create Subsystem description (CRTSBSD)

First of all we create subsystem description as below:

CRTSBSD   SBSD (AMINEM/MYSBSD) POOLS ((2 *BASE)) MAXJOBS(2)  TEXT('My  subsystem description')


Here, the subsystem job will run in pool 2 and will use *BASE for main memory storage. There can maximum of 2 jobs inside the subsystem at a time.


ü  Create Job queue (CRTJOBQ)


Then we create a job queue as below:



ü  Add Job Queue Entry (ADDJOBQE)

Once the job queue is created, then we attach the (ADDJOBQE) command, as follows:


MAXACT denotes the number of the jobs that can be process at the same time.


ü  Create Class (CRTCLS)

Class defines the run time attribute e.g. Run priority, Time slice, Default wait time, Maximum temporary storage etc.



ü  Add Routing Entry (ADDRTGE)



ü  Start Subsystem (STRSBS)


Once the subsystem is started it can be used to submit the job.


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