tspecific</B> is called on
the key whose thread specific data is being destroyed, the value NULL
is returned, unless <B>pthread_setspecific</B> was called previously
on that key from within <I>destr_function</I> to set the value to
non-NULL. For some implementations the effect of calling
<B>pthread_setspecific</B> from within <I>destr_function</I> can be
either memory leakage or infinite loops if <I>destr_function</I> has
already been called at least <B>PTHREAD_DESTRUCTOR_ITERATIONS</B>
times.</P>
<P STYLE=