Every association shall set up and maintain the reserves required by the board and may set up and maintain such additional reserves as are permitted by this chapter. The commissioner shall fix the amount of each association's separate reserve account to be set up and maintained for the sole purpose of absorbing losses (termed in this chapter "general reserve"), but in no event shall such amount of such general reserve be less than the amount required by the Federal Deposit Insurance Corporation. Transfers to general reserve shall be made at such time or times as set by the commissioner.