Socket Time-out Issues

I have socket client written in Java that sends a message to a socket
server running on the iSeries written in RPG. The socket server is the
spawning socket server based on Scott Klements code. I am having a
problem where the client times out but the server doesn't realize it. The
client sends a message and times out after 40 seconds if it doesn't receive
a response. The server receives a message, gets data, and sends a
response. Usually it only take a second or two. On the send of the
response, from the server, I check the response code. If the response code
is negative, I assume the client didn't get the response and back out the
change. The java developer assures me that once the timeout is reached,
the socket connection is ended by the client. I would expect to get a
negative response code on the send from the server, but that is not always
the case. This week we had some system issues causing the server to send
responses two or three minutes later. I would have expected the pipe to
have been broken in that amount of time.

Am I wrong to expect a negative response code on the send from the server?
Is there anything that I can tweak so the server recognizes the pipe is
broken by the client so that it will get a negative response code?

Thanks,
Mark Garton