Yes. These are now three caches, essentially. One for buffer pool, one for columnstore cache (32GB), and one per database for In-Memory table data (32GB per). This comes out of the total memory allocation for SQL, so if you set max memory to 128GB, you are sharing that among these three caches.
I don't know how that allocation takes place, but it's shared.
The other thing to be wary of is that there is other memory SQL needs to process work itself. This is cumbersome to track and understand, but part of the memory allocated to Windows is used here.