You could use the WRKACTJOB (and SBS parameter if you wish a specific subsystem) and redirect the output to a spool file. Then copy the spool file to a physical file, and then in a RPG program read the spool file just generated and get from it the job information to take an action. The previous steps of course could be in a CL program to do this automatically.
Or, you can take a look at the following link http://forums.systeminetwork.com/isnetforums/showthread.php?p=202516
There are third party products and other stuffs available to monitor your system from different purposes. But If you have to just automate monitoring of couple of jobs in a subsystem, the easiest way to do is WRKACTJOb and then scan through the SPOOL file (which is a rude way of doing it). You can achieve the same through APIs which I think will be more dependable. Refer ‘QUSLJOB’ API for your purpose.