Monitoring for System Request Menu Option 2

October 27, 2004 Hey, Ted

As part of our Sarbanes-Oxley compliance requirements, I have to write a CL program that temporarily changes the user’s user profile. (Adopted authority is not appropriate in this case.) One concern I have is that the program may end without executing the code that undoes the temporary change. I can use a global Monitor Message (MONMSG) command to trap unexpected errors and prevent an abnormal termination, but I also need to prevent the user from canceling the program by taking option 2 of the System Request menu. Is there a way to disable that option?

–Paul

The options that are executed from the System Request menu are stored in message CPX2313 of message file QCPFMSG. There’s no reason why you can’t modify or override the message so that option 2 executes some command other than End Request (ENDRQS), but I don’t recommend it. Let me suggest another approach.

If your program is a request-processing program, choosing option 2 from the System Request menu will cause your program to receive escape message CPF1907. By monitoring for this message, you will have complete control over the program and can handle the interruption as you please. Your request-processing program will also handle ENDRQS commands from called programs, unless they, too, are request-processing programs.

To make a program process requests, include the following commands.

sndpgmmsg msg('Request msg') topgmq(*ext) msgtype(*rqs)
rcvmsg    pgmq(*ext) msgtype(*rqs) rmv(*no)

There’s nothing magical about the contents of the MSG parameter in the SNDPGMMSG command. I use something that can’t be mistaken for a real command.

Put the messages at the top of the program, after the global MONMSG. In this way, you will be setting the program to trap the ENDRQS command from the start.

Here’s a short program by way of example. I hope it helps.

pgm

monmsg cpf0000 exec(goto CleanUp)

sndpgmmsg msg('Rqs msg') topgmq(*ext) msgtype(*rqs) 
rcvmsg pgmq(*ext) msgtype(*rqs) rmv(*no)

call SecPgm1 
call SecPgm2

CleanUp: 
/* clean up processing goes here */
endpgm

To learn more about request-processing procedures and programs, see the CL Programming manual at IBM’s iSeries Information Center.

–Ted

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