Unchained Stamina System...Please Explain?

[Palanan]

Could someone please explain the basics of the new stamina system in Pathfinder Unchained?

I can't get my hands on a copy of the book (never on the shelf in bookstores, back-ordered at the library) and I'm only hearing fragments about it. Is this something that reshapes melee? Is it remotely useful for casters, or ranged combatants?

[Ethereal Gears]

You get a pool of stamina point equal to your BAB + your Con mod. Your stamina pool regains 1 point per minute you spend not exerting yourself or fighting, up to this maximum. They're rewritten basically all the combat feats in all of PF to include additonal "combat tricks" which are special abilities you gain if you have that feat which require the expenditure of stamina points to perform. The book suggests either making a stamina pool available via a feat, or just giving it for free to fighters at 1st level and not letting other classes take it. I think that sorta sums it up.

EDIT: For example, if you have a stamina pool and you possess Spring Attack, you can spend stamina points to use Spring Attack as a standard action instead of a full-round action, just to take one example.