(a) The space in the old State Board of Insurance State Office Building, located on San Jacinto Street between 11th and 12th streets in Austin, the Sam Houston Building, and the John H. Reagan Building are allocated to the legislature and legislative agencies for their use.
(b) On written notice signed by both presiding officers of the legislature and delivered to the commission, the following buildings are allocated to the legislature and legislative agencies to the extent described in the notice: Lorenzo de Zavala State Library and Archives Building, Stephen F. Austin Building, Lyndon B. Johnson Building, and William B. Travis Building. On receipt of notice under this subsection, the commission shall begin immediately to undertake the relocation of agencies occupying space in buildings allocated to legislative use. The space must be made available for legislative use on a date determined by the presiding officers of the legislature.