title: START_STICKY not working
body: <p>I've asked a question about keeping service alive but I didn't find the solution so I have another simpler question.</p>
  
  <p>android doc says if android kills a service with START_STICKY on return of onStartCommand in low memory state, it will recreate the service if I'm correct.</p>
  
  <p>but this service gets killed and disappear in running tasks after a period of time but it didn't get recreated! I run this service in android 4.4.2 on my phone, when screen is on, it survived about 20 minutes 
  but when screen is off it disappeared after about 3 or 4 minutes... on my tablet (again android 4.4.2) it stayed longer, about 4 or 5 hours and then got disappeared again (I got different results on different tests). I even test it on android 5 and the result was similar to tablet with android 4.4.2</p>
  
  <p>am I missing something here? I thought service wont get destroyed when we are using return START_STICKY until I call stopService</p>
  
  <p>here's my service:</p>
  
  <pre><code>public class MyService extends Service {
      @Override
      public void onCreate() {
          super.onCreate();
      }
  
      @Override
      public int onStartCommand(Intent intent, int flags, int startId) {
          return START_STICKY;
      }
  
      @Override
      public IBinder onBind(Intent intent) {
          return null;
      }
  
      public void onDestroy() {
          super.onDestroy();
      }
  }
  </code></pre>
  
  <p>sry for bad english :)</p>