William H. Rincker has been elected chairman and chief executive of BSB  Bancorp and its BSB Bank and Trust in Binghamton, N.Y. 
Alex S. DePersis has been promoted to president and chief operating  officer of the both the holding company and the bank. 
  
Mr. Rincker has been president and chief executive officer of the bank  since December 1984 and recently completed 40 years of service with BSB. 
Mr. DePersis joined the bank in January 1985. Prior to joining BSB Bank  and Trust, he was vice president of commercial lending for Keycorp in   Broome County and was vice president and regional administrative officer   for Bankers Trust.