title: How does newCachedThreadPool cache thread
body: <p>Per the comment of method <code>public static ExecutorService newCachedThreadPool()</code> in <code>Executor</code> Class:</p>
  
  <pre><code>Threads that have not been used for sixty seconds are terminated and 
  removed from the **cache**.
  </code></pre>
  
  <p>I was wondering where is the cache and how it functions? As I didn't see any possible static <code>Collection</code> variable in the <code>ThreadPoolExecutor</code> or it's super class.</p>