Appendix F Checking and adjusting JXS limits

The number of jobs and suites which can be held by JXS is determined by data held in the JXS task description. These can vary between sites giving widely different maximum numbers of jobs; between 240 and 3000.

When running work with PXS the number of entries in the scheduler tends to increase, since more work is being scheduled at any one time, and the JXS limits should be re-examined.

The important ones are:

• Job quota. This should be set to at least 240kb for workloads of up to 1000 entries, and up to 360kb for larger or more active workloads. The total store quota for the VM will be the sum of the MXS, JXS and OXS quotas.
• Tag range. The scheduler tag range can either be "B" only, or "BCD", giving maximum workloads of 1000 or 3000 entries, respectively.
• Job limits. There is an EXS datum which controls the maximum number of jobs. On some versions of JXS this can be as low as 256.

F.1 Checking the limits

The JXS limits can be checked with the following command:

DTSKD( JXS, BASIC & UDATA )

The listing will look something like this:

*** DETAILS OF TASK PXS AT 11:38:14 ON 1992/08/12 *** 

UNIQUE                    YES

SHAREABLE                 YES

AVAILABILITY              9

LIBRARY                   :PXSDEMO.PXSSTDSW253

VM DESCRIPTION            2

OCF NUMBER                17

OPERATOR TAG              PXS

INITIALISATION PROCEDURES EXSINITIALISESCHEDULER

QUOTA                     120 K BYTES

POLICY                    7

*** USER DATA ***

*** DATA IN DIAGNOSTIC (TRWLD) FORMAT

TYPE RAK WAK LNTH DATA(CHARACTERS) DATA(HEX)

---- --- --- ---- ---------------- ---------

   1  15   8    1 ?                HEX(01)

   2  15   8    1 ?                HEX(07)

   3  15   8    2 AP               HEX(C1D7)

   4  15   8   25 :PXSDEMO.PXSBATC HEX(7AD7E7E2C4C5D4D64BD7E7E2C2C1E3C3)

                  HQUEUE253        HEX(C8D8E4C5E4C5F2F5F3)

   5  15   8    4 ????             HEX(00000100)

   6  15   8    3 BCD              HEX(C2C3C4)

   7  15   8    1 ?                HEX(80)

   8  15   8   14 ??????????????   HEX(0007000600050004000300020001)

   9  15   8    8 ????????         HEX(0000000000000100)

  10  15   8   20 ?PXSBATCH??????? HEX(08D7E7E2C2C1E3C3C8FF000000000000)

                  ????             HEX(00000078)

  11  15   8    1 ?                HEX(00)

 100  15   8    4 ????             HEX(00000004)

 101  15   8    1 ?                HEX(00)

 200  15   8   10 PXS254HOOK       HEX(D7E7E2F2F5F3C8D6D6D2)

*** END OF DATA IN DIAGNOSTIC (TRWLD) FORMAT

*** END OF USER DATA ***

*** END OF TASK DETAILS ***

The QUOTA can be read directly from the basic data. The tag range and job limits are held in the UDATA in TLD format as items 6 and 9 respectively. Item 9 in the example is in hex, and represents a job limit of 256 entries.

F.2. Changing the JXS limits

The JXS limits can be changed using CHANGE_TASK. QUOTA is changed using the QUOTA parameter while the UDATA items are changed via the GENDATA parameter and a HEX string as below. For simplicity the examples below are for 1000 and 3000 entries.

For 1000 entries the QUOTA should be 240KB and the GENDATA is:

HEX(060F0801) + "B" + HEX(090F08080000000000000420)

For 3000 entries the quota should be 360kb and the GENDATA is:

HEX(060F0803) + "BCD" + HEX(090F08080000000000000C20)

In both cases a few more entries are allowed for internal EXS use.