Application starts with 86% memory usage(HeapSize)

I'm developing application for Android(Xamarin). At current moment is like prototype(inside nothing heavy).
I added app7compat support library and also implemented toolbar with navigation Drawer Layout.
I make some test on real device(Samsung Galaxy S4 Active) and it's an like glitch/bug,because when application started,android device monitor showing this :

How that is possible? My activity contains:

1. Toolbar(with Drawer layout)
2. Some different controls,like imageView and imageButtons

As i said,that comes from start(i mean that this 86% used memory allocated with strange items,because there is no computing logic).
Why this happens? Thanks!