Yes, stack is a Scrabble word!

Verb

1. Load or cover with stacks

2. Arrange in stacks

3. Arrange the order of so as to increase one's winning chances

Noun

1. An orderly pile

2. (often followed by `of') a large number or amount or extent

3. A list in which the next item to be removed is the item most recently stored (LIFO)

4. A large tall chimney through which combustion gases and smoke can be evacuated

5. A storage device that handles data so that the next item to be retrieved is the item most recently stored (LIFO)