Stacks is a slur used to describe Blacks in a derogatory way. From the movie Goodfellas, character Stacks Edwards, the only black character, manages to fuck up the heist.
The word Stacks is a racial slur that has been used historically to degrade and dehumanize blacks. The word is still used by some people for this purpose, and it is seen as offensive and hurtful to blacks. If you are unsure about whether or not it is appropriate to use the word Stacks, it is best to err on the side of caution and avoid using it in any situation.