How to write this part ...by using cursor and string in COBOL

For each record found
Until i > 20

    Let local.sim_pref_list(i).sim_prefix
  = Lco_field_value(trim for spaces)

    Let local.sim_pref_list(i).length
= Get trimmed length from lco_field_value

     Let local.sim_pref_list.count= let local.sim_pref_list.count +1

Let i = i + 1

End for