In this section, “reserve account” means a continuing, nonlapsing account or fund in which money is retained to support appropriations that have become unfunded. By ordinance or local law, after notice and hearing, a county may establish one or more reserve accounts. An ordinance or a local law that establishes a reserve account shall provide for: requirements for the accumulation of a fixed amount of money, a percentage of designated revenues, or both; the circumstances under which the account may be used; and the use of any earnings on the account.