A lower limit for the eDir agent cache.
For smaller trees, those numbers can be way more than needed and therefor not efficient. From other readings and practice, I've been using twice the size of local "DIB Size (KB)" value (or whole tree on small shops) rounded up. So far it has appeared to work well for my clients.
I have seen indications of avoiding going over 1GB, though I am not sure if that is still an old 32-bit issue or a real issue, so something to watch on modern systems that can have lots of RAM, especially on VMs that we could grow the RAM along the way.