Changing the distribution list cache size

Hey guys,

Page 29, EV Performance Guide 10 talks about making the following change in a large organisation.

Enterprise Vault caches distribution lists and holds up to 50 distribution lists in
cache. Large organizations are likely to have more than 50 lists. To keep distribution
lists in cache longer, the following registry value can be changed. This has an impact
on the process’s memory use.

DWORD: DLCacheSize - raise to 400

I have been unable to find anything on how this cache works, can anyone enlighten me?