an #:max-threads.
</p>
<p>Thread pool objects with a #:min-threads setting of greater than 0 are
usually best kept as top level objects, because the minimum value of
threads will keep alive in the pool until thread-pool-stop! is called.
If such a thread pool is constructed within a local lexical scope,
then either thread-pool-stop! must be applied to the pool before that
scope is exited, or the last task added to the pool should itself
apply thread-pool-stop! to the pool (which it can do if &rsquo;non-block