What is the storage space required for this application?
This is what the system requirements says:
"Your PC must have 4GB of disk space available for storing Android apps / games and their data."
As you can see, a minimum of 4GB of space you need to have free on the partition where Bluestacks is installed. For additional information, consult the following page: http://support.bluestacks.com/hc/en-us/articles/204883885-BlueStacks-app-player-installation-requirements-