Non-Stop
Non-Stop is a cheat code in this game which makes it so collecting any Power Star causes Mario to not leave the level but stay in it and he can continue collecting Power Stars. This also means you get only 3 saves (from the cap switches) in the whole game so there are versions where you can toggle it so that the player can save the game more.
Code
The Non-Stop codes for the Japanese and English Versions of Super Mario 64 can be found at https://sites.google.com/site/sm64gameshark/codes/non-stop