Maximize memory total capacity in resource allocation

Hello, I have question about memory allocation in ESXi 6.0.

I don't need memory sharing and I want allocate maximum memory VM.

I have total 96GB of memory.

In "Configuration" - "System resource reservation", says Memory 4GB is reserved

In "Configuration" - "Memory", says System uses 400MB.

In "Resource Allocation", "Total Capacity" is 89GB.

My question is, where are defined missing 3GB?

And main question, is it possible define memory size for ESXi itself, says 1GB is enought?, and remaining 95GB have available as "Total capacity" and reserve it for VM?

Thank you.