Sure, it's fine. One thing I did start doing a couple of years ago was opening the cases, removing the lids and rings, checking the jars, then turning the jars upside down back in the box for storage.

Lucky I did - I found 6 chipped jars and 2 cracked ones (honestly, that's the first and only time it has ever happened to such an extent) so I was able to get replacements without any hassle.

Stacking at storage is No problem as opposed to stacking in transport. In static (no movement) condition you may stack them as high as you want as long is there is no risk if tipping over.

Lets say 1 jar weighs 12 oz. If you stack 50 of them, the one at the bottom will carry 588 zo = 37 lbs. I am sure each jar is capable of handling much more load than that, safely. Though you are not going to stack them nearly that high.