The MAP DYNAMIC statement names the variables and  arrays  whose  size
  and  position  in  a  storage  area  can  change at run-time.  The MAP
  DYNAMIC statement is used in conjunction  with  the  REMAP  statement.
  The  REMAP  statement defines or redefines the position in the storage
  area of variables named in the MAP DYNAMIC statement.

  Example

  MAP (ABC) STRING DUMMY = 512
  MAP DYNAMIC (ABC) STRING A, B, C, LONG D, E, F