How much room does it require to store 50000 dollars in US 100 dollar bills?

Not much. Storing $50000 in hundred-dollar bills would require 500 bills. Current US banknotes are 0.11 mm thick on average so 500 would make a stack only 500 × 0.11 = 55 mm high. All bills have horizontal dimensions of 156 × 66.3 mm so you could easily hold the entire stack in one hand. For comparison, that's (very) roughly the volume of four packs of playing cards.