Changing the storage threshold for the system auxiliary storage pool

It is important to prevent the system auxiliary storage pool (ASP) from filling to capacity. If this occurs, the system ends abnormally. You can try to avoid this by specifying a storage threshold that warns you of a potential space shortage.

One way to establish this threshold is through dedicated service tools (DST) or system service tools (SST). Use the same procedures as you would when setting the storage threshold for any other ASP.

Note: Establishing the threshold through DST will not prevent the system from ending abnormally. It will only notify you when the system ASP reaches the capacity threshold.

You can also protect the system ASP from filling to capacity by using the QSTGLOWLMT and QSTGLOWACN system values. The QSTGLOWLMT system value specifies the percentage of unallocated auxiliary storage that is remaining when the critical storage lower limit is reached. If the system reaches that limit, the QSTGLOWACN system value specifies what action the system should take. Using this method allows the system to actively prevent an abnormal shutdown instead of sending a warning of the condition.

Note: Using these system values does not affect any existing storage threshold that you might have set through DST.

You can use the QSTGLOWLMT and QSTGLOWACN system values on the following commands:

CHGSYSVAL          RTVSYSVAL
DSPSYSVAL           WRKSYSVAL

The following procedure demonstrates how to use these system values. (The Work with System Value (WRKSYSVAL) command is used as an example.)

  1. At a command line, type WRKSYSVAL and press Enter.
    You are shown the Work with System Values display.
                               Work with System Values
                                                       System: YOURSYS
Position to  . . . . .   _______  Starting characters of system value
Subset by Type . . . .   _______  F4 for list
 
Type options, press Enter.
  2=Change   5=Display
 
         System
Option   Value       Type    Description
  _      QSTGLOWACN  *STG    Auxiliary storage lower limit action
  _      QSTGLOWLMT  *STG    Auxiliary storage lower limit
  2. Type a 2 in the option field to change QSTGLOWACN and press Enter.
    You must have *ALLOBJ and *SECADM authority to change QSTGLOWACN. You are shown the Change System Value display.
                                  Change System Value
 
System value . . . . . :   QSTGLOWACN
Description  . . . . . :   Auxiliary storage lower limit action
 
 
Type choice, press Enter.
 
  Action . . . . . . . .   *MSG_______     *MSG
                                           *CRITMSG
                                           *REGFAC
                                           *ENDSYS
                                           *PWRDWNSYS
  3. On the Change System Value display, type the name of the action that you want the system to perform after reaching the critical storage lower limit.
    Press the Enter key. The actual actions that are performed by the action names are as follows:
    *MSG
    The system sends the CPI099C message to the QSYSMSG and QSYSOPR message queues. (The system also sends this message when you select any one of the other actions.)
    *CRITMSG
    The system sends the CPI099B critical message to the user who is specified in the service attribute to receive critical messages.
    *REGFAC
    The system submits a job to call exit programs that are registered for the QIBM_QWC_QSTGLOWACN exit point.
    *ENDSYS
    The system ends to the restricted state.
    *PWRDWNSYS
    The system powers down immediately and restarts
  4. From a command line, type DSPSYSVAL and press the Enter key.
    The Display System Value display is shown.
                                 Display System Value
 
System value . . . . . :   QSTGLOWLMT
Description  . . . . . :   Auxiliary storage lower limit
 
Lower limit  . . . . . :   1.0000        0-100 percent
    The lower limit value is the lowest amount of unused storage that can exist in the system ASP before the system performs the QSTGLOWACN action. (You can use the WRKSYSSTS command to view the amount of storage that is currently being used in the system ASP.) The system is shipped with the QSTGLOWLMT system value set to 5.0. Any change you make to this system value takes effect immediately.