40d:Stack

A stack is a pile of like objects, such as food or ammo. A stack is considered a single object for purposes of hauling, but single, individual objects can be used from it, one at a time, such as one bolt shot from a crossbow, or one food item taken for eating. If the item survives that use (the bolt doesn't break, or the food item is dropped for some reason), it then becomes an individual item, unconnected to any stack. Individual items cannot be stacked or re-stacked.

Stacks of items are counted as the total number in the stack for purposes of storing in barrels or bins, as will items produced in workshops for determining clutter - this can occur very quickly with some items.

Items can be viewed a number of ways, but the easiest is via the k key; a stack of 4 plump helmets would look like this:

Plump Helmet [4]

Plants grow in stacks of 2-5 items*. Butchering an animal produces a stack of meat and a stack of bones equal to that creature's size (as does rotting for bones). Prepared meals come in stacks of size equal to the total of the items used - since up to 4 stacks can be used to cook a lavish meal, this can be quite large. Bolts come in stacks - 25/ for wood or metal bolts, and creating bone bolts from a stack of bones gives a stack of bolts equal to 5x the bone stack size. (Immigrants can bring bigger stacks.)

(* Farming crops actually produces from 0-5 of that plant type, but "0" and "1" are usually not referred to as "stacks", for obvious reasons.)