1.
If you ask how one person or thing stacks up against other people or things, you are asking how the one compares with the others. ( INFORMAL )
How does this final presidential debate stack up and compare to the others, do you think?
= compare
PHRASAL VERB : no passive , V P
2.
If facts or figures do not stack up , they do not make sense or give the results you expect.
There have been a number of explanations, but none of them stack up.
PHRASAL VERB : V P
3.
see stack 2