Local cache size - dynamic?

Question,

Assuming I set a desktop policy to use 5% of free disk space, and free disk space is 20GB, so cache size will be 1 GB.

Now - if user cleared his hard drive, and now he have 40GB free of disk space, will the vault cache recognizes the change and increase the cache to be 2GB? 

Or only once the vault cache is being built this is set?