Is Shared Memory bound to a thread in Linux ?

By that I mean, if you allocate shared memory in a thread , does that shared memory go away when the thread goes away ?

I have a program which is exhibiting that behavior, and i am surprised, because I believe that shared memory is a process wide resource - so if a thread allocates a shared memory resource, that resource should be available to other threads after the allocating thread has gone away; that is how threads behave on Solaris and AIX.

This is with posix threads by the way, and LInux kernel 2.4 on redhat EL 3.

Thanks,
Colm.