The Treasurer may enter into an agreement or an indenture of trust with a commercial bank or trust company authorized to do business within or without the state to act as trustee for the benefit of the holders or owners of bonds, notes or other obligations of the state, to provide for the timely payment of principal and interest on or repurchase of such bonds, notes or other obligations, and for payments under any agreement entered into pursuant to section 3-20a, from funds deposited at the direction of the Treasurer with such trustee, subject to the approval of such agreement or indenture of trust by the State Bond Commission. Such agreement or indenture of trust may include provisions regarding the establishment and maintenance of reserves, sinking funds and any other funds and accounts as shall be approved by the State Bond Commission in such amount as may be established by the State Bond Commission, and the regulation and disposition thereof, including requirements that any such funds and accounts be held separate from and not be commingled with other funds of the state and to deposit therein any moneys appropriated for the payment of such principal and interest. Any moneys in such fund or funds which remain unexpended at the end of any fiscal year shall be carried forward to the next fiscal year.