stacks vs storage space

stacks and storage space both are nouns.

Word	Noun	Adjective	Verb	Adverb
stacks	Yes	No	No	No
storage space	Yes	No	No	No

As nouns, storage space is a hypernym of stacks; that is, storage space is a word with a broader meaning than stacks:

stacks: storage space in a library consisting of an extensive arrangement of bookshelves where most of the books are stored
storage space: the area in any structure that provides space for storage

stacks (noun)	storage space (noun)
storage space in a library consisting of an extensive arrangement of bookshelves where most of the books are stored	the area in any structure that provides space for storage
a large number or amount