The Secretary of Finance during the last month of the fiscal year may set aside, from unexpended appropriations, a sum sufficient to pay all bills for which requisitions have been issued in accordance with this chapter during the fiscal year, but which remain unpaid. No such sum shall be set aside for the purpose of paying state employees' salaries or wages which do not become due and payable until the next fiscal year. Funds so set aside shall not lapse or revert at the end of such fiscal year and shall continue to be available in the fiscal year following until reverted by the Secretary of Finance. In no instance shall such funds continue beyond June 30 of the fiscal year following.