For Windows it seems possible to control the amount of memory MongoDB uses, see this tutorial at Captain Codeman:
Limit MongoDB memory use on Windows without Virtualization
Add a line as below:
@mongodb - rss 33554432
and then save the file.
It will take effects right away.
In this example, we assign 32GB memory usage for mongodb group users
Do you mean memory usage or disk space? If you are really talking about memory, then Mongo stores its data in memory-mapped files, giving the illusion of massive memory usage.
You will find more information here: