only 8GB diskspace, iCloud keeps downloading iCloud stuff!!! help! Macbook: 128GB - 8GB free 
iCloud: 200GB - 160GB free


I have a very frustrating problem. I have a 128GB Macbook so you can imagine how space is an issue. I bought 200GB iCloud storage thinking that would copy non-essential stuff to iCloud and free up space. I have PLENTY of iCloud storage left but it is no comfort because it does nothing to keep my MacBook free. It seems to keep about 8GB free.. which isn't quite enough to even download a new Xcode version. 

I nearly bricked my MacBook by downloading a Mac osX update and it getting stuck half way through with "low disk space" issues. 

Searching for large files shows these "iCloud Synchronization files" on my hard drive taking up valuable space!! But I can't unsync them and keep the file in the cloud. It appears I have no control over whats synced.

Is there a setting somewhere that says "try keep xGB free"? Or is there at least an "unsync" command on a synced iCloud file?
The answer for me is to turn OFF the Optimize setting (see image). It seemingly stopped filling up the harddrive after I changed that setting.