I have 1000 rolls of Arista Premium 400 cold stored b/c they are no longer making it. As it's my every day workhorse film that amount should last me 3-4 years. I've also stocked up on 20 rolls each of: Delta Pro 3200, Tmax 3200, Neopan 400, Plus-X 125, and Lomo 110 color and black/white.
On top of all that I have a couple hundred rolls of various expired and infrared films.
Not sure if that's considered stockpiling, but I do have more in stock than my local lab.