Writing a power-handling program

A power-handling program should be activated at each IPL and remain active at all times. It should be accounted for in the activity level available in work management subsystem specifications.

ALCOBJ OBJ(xxx/yyy *MSGQ *EXCL)

You can choose to ignore the other messages.

Your program can handle a brief power interruption without doing any unique processing. For example, when the CPF1816 message arrives, you can set a switch in your program that indicates that the message occurred. The program might then perform a RCVMSG with WAIT(10) to cause a time-out in 10 seconds. If the CPF1817 message is received before the time-out occurs, you can reset the switch and perform no other action.

ENDJOB OPTION(*CNTRLD)

This sets an indicator to end the job. Some higher level languages and the control language allow you to test within a program to see if a controlled ENDJOB was specified. If the program does not end itself, the default on ENDJOB (30 seconds) is used.

You can set a second timer in your program, such as RCVMSG WAIT(120). If utility power has not been restored, you can issue the PWRDWNSYS OPTION(*IMMED) command. The wait time should be specified based on your battery time and the time that is required for a power-down.

For example, when performing a SAVSYS (Save System) or RCLSTG (Reclaim Storage), your uninterruptible power supply program will no longer be active once all subsystems have been terminated. Only a single workstation job will be active. You can perform one of the following actions as an alternative:

1. After all subsystems have been ended, from the command line change the mode for the message queue specified in system value QUPSMSGQ to *BREAK. This will cause all uninterruptible power supply messages to be sent as break messages to the user signed on to that workstation. With this method the user will manually decide what to do should a power failure occur.
2. Change the system value QUPSDLYTIM to some value other than *NOMAX (for example, the number of minutes you want the uninterruptible power supply to ride out the power failure). This method will prevent the system from performing an immediate quick shut down. However, if a power failure occurs, a quick shut down will be performed if the power failure lasts longer than the value specified for the system value QUPSDLYTIM.
3. Change your existing uninterruptible power supply handling program for use as a BREAK HANDLING program which may be used while the system is in a restricted state. This can be done by creating a second version of your uninterruptible power supply program that does not allocate the message queue specified in system value QUPSMSGQ. (In other words, do not use the ALCOBJ command.) To utilize this program while in a restricted state, before starting a dedicated function such as SAVSYS, enter the command:

   CHGMSGQ MSGQ(LIB/MSGQ) DLVRY(*BREAK)
   PGM(LIB/PGM)

   where (LIB/MSGQ) is the name the message queue specified in system value QUPSMSGQ, and (PGM/LIB) is the name of your modified uninterruptible power supply handling program. Now, should a power failure occur, the power failure message will be handled by the break handling program, even while a function such as SAVSYS is running. To deactivate the break handling program either have the user sign off or enter:

   CHGMSGQ MSGQ(LIB/MSGQ) DLVRY(*HOLD)
   PGM(*DSPMSG)

   Once you have deactivated the break handling program, you should immediately start your subsystems and your normal uninterruptible power supply handling program.

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• Example: Power-handling CL program
  You can use the sample program with a full uninterruptible power supply.
• Example: Testing a power-handling CL program
  Once a power-handling program has been created, you can test it by creating a simple CL program that uses the Send Program Message (SNDPGMMSG) command and the Delay Job (DLYJOB) command. Set the DLY parameter value on the DLYJOB command to meet your testing needs.