Memory store changes in elasticsearch 1.7.x

I am running a 0.90.x cluster using memory store, and i am working towards upgrading to 1.7.x

My setup was basically a handful of nodes with a 3GB heap, and memory store makes them write into direct memory outside the heap.

When I tried to test the setup on 1.7.x, the memory store seems to write it into the heap, which is definitely not preferred due to inefficient storage, garbage collection impact, and the java compressed pointers deal.
Is there a configuration to set it to write to Direct Memory like before?
OS: Windows Server 2012

Not that I know of, also beware that memory store is removed in 2.0.beta1 already. You might want to look into using ordinary store instead, have a look at for the removal PR.