53 Pa. Stat. § 14757
In order to avail itself of the powers conferred by this act, the mayor of any such city shall appoint a commission of seven or more members, to be known as the Zoning Commission, to recommend the boundaries of the various districts and the appropriate restrictions and regulations to be enforced therein, and to include in such recommendations such maps, charts or prints as it may deem necessary, desirable or convenient, to show the locations and boundaries of the respective districts in which such regulations and restrictions shall apply. The said recommendations shall be in the form of a proposed zoning ordinance, and shall provide for a board of adjustment, a bureau of zoning, and the rules and regulations for the administration of said ordinance by the said bureau in accordance with the provisions of this act. The zoning commission shall make a preliminary report, and hold public hearings thereon, before submitting its final report, and the council of such city shall not hold its public hearings or take action until it has received the final report of such commission.
53 P.S. § 14757