What constitutes a "cash stash"? For most people, between about $100 and $300. Some people like to keep several thousand dollars in "foldin' money" in their homes, in case of disaster. That may be excessive! But it's probably better to err on the side of too much cash, rather than too little.
Why bother keeping a wad of cash around? It's not JUST good for flinging up in the air while hollering "Make it rain!" when you get bored on a Sunday afternoon. (Not just!) There are several benefits to having a little backup money always on hand: