Ahem. And if you'll edit your post no one will.
From the title I can suggest two possibilities:
conf/battle/monster.conf
// Defines various mob AI related settings. (Note 3)// 0x008: If set, when a mob loses track of their target, they stop walking// immediately. Otherwise, they continue to their last target tile. When// set mobs also scatter as soon as they lose their target. Use this mode// to make it much harder to mob-train by hiding and collecting them on a// single spot (ie: GrimTooth training)
Or src/config/core.h
/// Uncomment to enable the Cell Stack Limit mod./// It's only config is the battle_config cell_stack_limit./// Only chars affected are those defined in BL_CHAR (mobs and players currently)// define CELL_NOSTACK
You have that one uncommented ^