|This article is about an older version of DF.|
A stack is a pile of objects, such as food, bones, or ammo, that came from the same source at the same time - the same farm plot tile, animal, or workshop job. A stack is considered a single object for purposes of hauling and jobs, 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.
- Plump helmet 
Plants usually grow in stacks of 2-5, depending on the skill of the planter (though fertilizer can potentially boost stack size as high as 10). Butchering an animal produces stacks of meat, chunks, and bones equal to that creature's size (as does rotting for bones). Prepared meals come in stacks of size equal to the total number of items used - since up to 4 ingredients can be used to cook a lavish meal, and each ingredient itself can be a stack, this can be quite large. Wooden and metal bolts come in stacks of 25 (though immigrants and invaders can bring bigger stacks, and adamantine bolts only come in stacks of 10), and bone bolts come in stacks 5 times as large as the stack of bones from which they were created.
Note that some stacks of items do not behave as might be expected. When making bone crafts, crossbows, or armor, a stack of bones will produce the same number of goods as a single bone, making stacks of bones highly uneconomical for making anything other than bolts.