Android - strange app Heap behavior

I measure acutal allocated RAM of my Application by DDMS and it's cause GC, which shows actual allocated RAM.

I have made simple project of activities, which goes one by one. Here is status of memory allocation (in MB):

----> I am opening activities

Begin > 2,258 > 2,305 > 2,335 > 2,366 > 2,390 > 2,419 > 2,441 > 2,472 > 2,496

And now I go back to the first activity:

                     I am closing activities        <----

...End < 2,315 < 2,318 < 2,340 < 2,370 < 2,392 < 2,423 < 2,445 < 2,477

My results - despite I have returned back to the starting point of my app, there is about 60kB bigger allocated space? Why so? I am certain, when I try open m开发者_Go百科ore intens this way and then close them, the difference would be bigger. Does my App holds at the ...End point still some "traces" of references to last activities?

Thx

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Make sure to release all references in the ondestroy method of your activities.