Stack Up Meaning

(idiomatic, transitive) To put a group of abstract things together.

Example:   stack up the boxes.
  stack up memories.
To compare with something; to measure up. (Often used with "against", "among")
1973, The Paper Chase, 01:17:10
  This is a great outline. Fantastic. If your's doesn't stack up, you wont get a chance to look at it.
1939, Milwaukee Journal, issue of 7th September, page 3:
  "How Populations Stack Up Among Nations At War" (name of the article)