Kosik was born in Dupont, Pennsylvania. He received a B.A. from Wilkes College in 1949. He received an LL.B. from Dickinson School of Law in 1951. He was a Corporal in the United States Army from 1943 to 1946 and a Reserve Colonel in 1975. He was in private practice in Scranton, Pennsylvania from 1951 to 1953, became an assistant U.S. Attorney of the Middle District of Pennsylvania from 1953 to 1958, before returning to private practice from 1958 to 1969. He was a Chairman, Pennsylvania State Workmen's Compensation Board from 1964 to 1969 and became a judge on the Court of Common Pleas, 45th Judicial District of Pennsylvania from 1969 to 1979. He became a President judge, Court of Common Pleas, 45th Judicial District of Pennsylvania from 1979 to 1986.