SUBROUTINE PUSH (A, B, C) 
    
      INTEGER  PSTACK (12)  
      INTEGER  PX   
      INTEGER  PEND 
      COMMON   /PPCOM/  PSTACK  
      COMMON   /PPCOM/  PX  
      COMMON   /PPCOM/  PEND
      INTEGER A, B, C   
      IF (PX .GT. PEND) CALL FATAL (45) 
      PSTACK (PX) = A   
      PSTACK (PX+1) = B 
      PSTACK (PX+2) = C 
      PX = PX + 3   
      RETURN
      END