Section 13-129. Contributions of the city and their use; pension fund

a. The
  pension  fund  shall  be  the  fund  in  which  shall be accumulated the
  reserves necessary to pay, and from which shall be  paid,  all  pensions
  and  all  pensions-providing-for-increased-take-home-pay  and  all other
  benefits allowable by the city on account of all service of  members  to
  whom prior-service is allowable as provided in this chapter.
    b. Upon the basis of the mortality and other tables herein authorized,
  and regular interest, the actuary shall compute the amount of the single
  contribution  which,  if  paid  into  the  pension  fund  at the time of
  entrance into the retirement  system  of  each  such  member,  would  be
  sufficient  to  cover the total liability assumed by the pension fund on
  his  account  for  the  payment  of  future  benefits,  other   than   a
  pension-providing-for-increased-take-home-pay.
    c.  Until  the amount accumulated in the pension fund becomes not less
  than the present value of all amounts  thereafter  payable  through  the
  pension fund on account of members who have not been retired, other than
  amounts  payable for pensions-providing-for-increased-take-home-pay, the
  aggregate amount annually due to the pension fund shall be six per  cent
  of  the  sum  of  all  such  single contributions, but not less than the
  amount payable from  the  pension  fund  in  the  ensuing  fiscal  year,
  exclusive       of       the       amount       so      payable      for
  pensions-providing-for-increased-take-home-pay.
    d. Contributions shall be paid into the pension fund,  in  the  manner
  and  to  the  extent  specified  by  section  13-152 of this chapter, to
  provide reserves-for-increased-take-home-pay.