n-blocking status of the thread pool.  If
&rsquo;val&rsquo; is #f, the thread-pool-stop procedure will block, if #t it will
not.  (See the documentation on the thread-pool-stop! procedure for
more information about this.)
</p>
<p>This procedure is thread safe (any thread may call it).
</p>
<p>This procedure will throw a &rsquo;thread-pool-error exception if it is
invoked after the thread pool object concerned has been closed by a
call to thread-pool-stop!.
</p>
<p>This procedure is first available in versio