MAX_ENTITY_CRAMMING
The maximum number of other pushable entities a mob or player can push, before taking 3 suffocation damage per half-second.
Damage affects survival mode or adventure mode players, and all mobs but bats. Pushable entities include non-spectator-mode players, any mob except bats, as well as minecarts and boats.
Setting to 0 disables the rule.
This is a numerical game rule, with a default value of 24.