RouterBoard run out of memory

A simple and precisely question it is a lame ? since 2 days I search entire internet and not find a clear answer.
2013 10 30 Mik Max Cache Error.jpg
With Max Cache Size left Unlimited as someone from Mikrotik recommend here up … a customer playing God Game Empire … because of the traffic … make RB450 to be rebooted by watchdog in max 1 hour and this affect other users connected to the same router.

InoX please advice what settings should I place in Max Cache to represent 36 MiB from top of the WinBox window ? simple question.