Is it possible to reserve exact amount of space for the indexing and virtual memory?

Is it possible to reserve exact amount of space for the indexing and virtual memory?

I have Macbook Air with 128 GB SDD (with OS X Yosemite). When I run out of memory (free space less than 1 GB) the computer slows down and even hangs up.

I suspect that this slow down is due to the impossibility of indexing to be written on the disk and due to a lack of space for the virtual memory.

Is it possible to single out a place to be used only for paging and indexing? For example, to reserve 10 GB for that purpose?

In Linux systems there is a /var folder where these kind of stuff are written. It can be put on a separate partition and this way to reserve certain amount of space only for itself. Is it possible to do something like this on a Mac in regard to indexing and virtual memory? I would sacrifice 10-15GB for it, if is needed.