Also LOLOLOLOLOLO you got no idea how smash64 works - "jab usmash on top platform gimps are my fav."
The area in which you do this doesn't matter, it's a gimp regardless at certain % on some characters, but catching people or stopping them with a jab is much different which is what I assume you were thinking. There are several working ways to end up with a jab to upsmash, on Link you could uair twice then utilt 3 or 4 times and uair again then full jump Bair jab upsmash. However that, doesn't always work on most character because you got to utilt them multiple times which they can easily di to one side and mess up.
You may not look stupid to these other people, but to me your ignorance is showing.