 <B>NULL</B>
with all keys. 
</P>
<P><B>pthread_key_create</B> allocates a new TSD key. The key is
stored in the location pointed to by <I>key</I>. There is a limit of
<B>PTHREAD_KEYS_MAX</B> on the number of keys allocated at a given
time. The value initially associated with the returned key is <B>NULL</B>
in all currently executing threads. 
</P>
<P>The <I>destr_function</I> argument, if not <B>NULL</B>, specifies
a destructor function associated with the key. When a thread
terminates via <B>pthread_exit<