Established TCP connections not crossing more than 400 on particular socket

Established TCP connections not crossing more than 400 on particular socket

I written one program in java which handles request from particular
socket. Some times request comes concurrently we can say 1000/sec and that
time ESTABLISHED TCP connections touched around 400. When ESTABLISHED
connections touched 400 then socket start refusing the request and then I
miss my reporting. Can I increase ESTABLISHED TCP connections on
particular port ? Any time wait condition for ESTABLISHED TCP ?