From WordNet (r) 3.0 (2006) :
stacks
n 1: a large number or amount; "made lots of new friends"; "she
amassed stacks of newspapers" [syn: tons, dozens,
heaps, lots, piles, scores, stacks, loads,
rafts, slews, wads, oodles, gobs, scads,
lashings]
2: storage space in a library consisting of an extensive
arrangement of bookshelves where most of the books are stored