Notwithstanding any other provision of this section, the authority of the Secretary to enter into agreements making resources available under this section shall be limited to such amounts as are appropriated in advance in appropriation Acts. Effective October 1, 1978, there are hereby authorized to be appropriated to the Secretary of the Treasury, without fiscal year limitation, such sums as are necessary to carry out subsection (a) of this section, but not to exceed an amount of dollars equivalent to 1,450 million Special Drawing Rights.