Cleaning up Resources Occupied by the Thread

Hello All,
         I am a newbie of this group....I have written a process which
would create maximum no of threads in the Linux 9 Environment. It
creates maximum of 255 threads including the main process. But my
implementation should kill one of the thread and need to recreate a
new thread. If i do so i am unable to recreate the thread and
pthread_create return no memory. I tried with pthred_kill and also
with pthread_detach. It seems the thread resources are not cleaned up
after calling pthread_create or pthread_kill. Please help me out of
this.