eh, a stamina system is best done for a specific map..
I know mine is tied in with 3 other custom unit attributes =P-
food- low food can decrease stamina regeneration as well as morale
experience- high experience can decrease stamina cost and increase morale given off and general morale
morale- low morale can lower attack speed and move speed and high morale can increase attack speed and move speed
stamina- low stamina can lower morale, attack speed, move speed, and armor
would you like to join the team for the map I'm working on right now? : )