shrinking available ASP

Hello Midrange-L,
     First of all, we would like to thank all of you who responded to our
postings this past year.  Your insights, perspectives, and advice were
great.  We appreciate each of you, and the list, very much.
     We also have a new question.  We recently changed most of our reporting
programs from interactive to batch.  This has worked out great, but we've
noticed that our ASP usage has increased.  It seems to creep up steadily
until we IPL the box or at least end the major subsystems, whereupon it
drops back to where it started.
     What types of processes would hold storage in such a manner?  Is there
a way to see what might be using and holding ASP resources?  What is
released at ENDSBS time?  We've added more storage so we're not truly
constrained, but it does seem puzzling that ASP utilization seems to
steadily creep upward.