Skulls & Shackles
When you have an ability that grants you stamina points, you gain a stamina pool with a maximum number of stamina points equal to your base attack bonus + your Constitution modifier. During combat, you can spend stamina points from this pool to perform a combat trick, the specific effects of which are dictated by a combat feat you possess. Spending stamina points in this way is not an action, but you can’t do so if you are unconscious, fatigued, or exhausted. You can use as many combat tricks on the same action or attack as you like (as long as you have the stamina points to spend), but you can’t use the same combat trick twice within its scope. For instance, if you have a combat trick that affects a single attack, you can’t use that combat trick more than once on the same attack.
Dropping to 0 stamina points causes you to become fatigued until you have 1 or more points in your stamina pool.
Temporary increases to your Constitution score, such as those granted by the core barbarian’s rage class feature or bear’s endurance, do not increase the number of stamina points in your pool or your pool’s maximum number of stamina points. However, permanent increases to Constitution, such as the bonus granted by a belt of mighty constitution worn for more than 24 hours, do adjust your stamina points.
You regain stamina points by resting for short periods of time. You don’t have to sleep while resting in this way, but you can’t exert yourself. You stop regaining stamina points if you enter combat; take an action that requires a Strength-, Dexterity-, or Constitution-based skill check or an ability check tied to one of those ability scores; or take more than one move action or standard action in a round (you can still take free, immediate, and swift actions). This reduction in your number of actions per round also effectively halves your overland speed. For each uninterrupted minute you rest in this way, you regain 1 stamina point. If you are suffering from any of the following conditions, you can’t regain stamina points: confused, cowering, dazed, dead, disabled, exhausted, fascinated, frightened, helpless, nauseated, panicked, paralyzed, petrified, shaken, sickened, staggered, or stunned.