 on
that macro below).
</p>
<p>If &rsquo;delta&rsquo; is negative and results in a max-threads value of less than
the current number of running threads, the number of threads actually
running will only be reduced as tasks complete, or as idle timeouts
expire.  The maximum number of threads will not be reduced by this
procedure below the min-threads value, or if that value is 0, below 1.
</p>
<p>This procedure does nothing if thread-pool-stop!  has previously been
called.  This procedure is thread safe - any