49016e78_rver_Features___Hack_Mine_Wiki__Description
[Property] emergencyResetSize [Default Value] 131072 [Description] 
An upper bound on your cache size that, once exceeded, forces the area cache to entirely reset (like the "/reset-ac" command.) Basically, set it to an amount you know will never be exceeded, like 50 times the maximum players on your server (since a player isn't liable to need more areas than can appear on their radar, 50 areas per player is an incredibly generous estimate you can be 99.999% certain is the result of erroneous growth.)
Server Features - Hack/Mine Wiki
Description