OOM with threads in wait state

[vksiva]

We have been using quickserver for many years now, we recently have hit an issue with the instance.

It throws an "OutOfMemoryException: Cannot create a native thread". I am attaching the thread stack.

Q1) I do see a GhostReaperThread in the thread stack - will that cleanup any threads that are in the wait state?
Q2) When does it come out of wait() state?
Q3) If the pool size is set to 300, why are there 600+ threads created?

Please can you help us out here. Also, let us know if you need any more information?
qs-jstack.txt