An "emergency stash" refers to a small amount of something valuable or necessary that is kept hidden or saved for unexpected or urgent situations. It is like a backup or reserve that can be used when you really need it. Full definition
I have about $ 50,000 in savings, so I could theoretically expunge all debt from my record and officially be debt free in one fell swoop, and still have a moderate emergency stash. (money.stackexchange.com)
That's my emergency stash in case I am running through the airport and don't have time to grab a bite to eat. (inc.com)