TCP/IP Configuration and Closed Ports

I have an C Server application that was compiled on V3R7 for V3R1.  It was
installed under V5R1 and ran with no problems.  Since we upgraded to V5R2,
when the remote system ends the connection, the port stays in the closed
status until we end the job.  Taking option 4 from the netstat *cnn screen
on the closed connection does not make it go away.  We did not have this
problem before the upgrade to V5R2 from V5R1.  The remote system closes all
connections every night for a maintenance cycle.   We only IPL our system
once a month so I end up with pages of these closed connections tying up
multiple outbound ports.

The C Server application has two modules in it, one is C and the other is
RPGLE.  Every thing is fully optimized and contains no debug data.

Is there a new TCP configuration setting I am missing that will close these
lingering connections?  An suggestions I can pass to the vender to fix it on
their end?  Would re-installing and translating under 5.2 possibly fix it
since it was compiled for V3R1 using a V3R7 machine?

TIA

Christopher K. Bipes 
Manager of Systems Administration
CrossCheck, Inc.