HANA Indexserver memory calculations

Hi Guys,

We have standalone Hana implemented in our company. I've found  indexserver memory consumption in 230GB.

Out of 230gb  I can  see 180GB consumed by below tables but not sure of what consumes the other 50GB? How can i verify this 50GB? Also each time i look for indexserver memory it goes up and down. Can someone please throw light on this???

100GB for cloumn tables size

50GB for cloumn tables size

30GB is Stack & Code size.

50Gb ?????????

Thanks & Regards

Raj