HTTP Jobs hanging up

I'm experiencing a frustrating problem on our web server (running Apache on 
V5R1). 

Recently, the server started hanging jobs for no apparent reason.  By hanging 
jobs, I mean that I get several HTTP jobs that never stop running and devouring 
CPU -like a program stuck in an endless loop.

I can end the jobs to recover.  Sometimes I won't see it for days and sometimes 
it will happen five or six times a day.  I can work with the job before I end 
it and I have retrieved the program and statement number (this appears to be 
the only consistency), but according to the compile listing the statement is an 
ENDSR and I don't see how a program could get endlessly stuck on an ENDSR.

Most frustrating of all is that I cannot reproduce the problem and I cannot 
seem to isolate a set of like circumstances.  Is their a way I can get a 
program dump from a program that is running?

Thanks,

Joel