如何程序进入的时候自动设置成上次退出时的值

REPORT  ZDEMO_GETPARAMETER                      .

SELECTION-SCREEN BEGIN OF BLOCK BK WITH FRAME TITLE TITLE01.
PARAMETERS:      P_MBLNR LIKE MSEG-MBLNR OBLIGATORY .
SELECTION-SCREEN END OF BLOCK BK.

INITIALIZATION.

  GET PARAMETER ID 'Z11' FIELD P_MBLNR.

START-OF-SELECTION.
  SET PARAMETER ID 'Z11' FIELD P_MBLNR.
END-OF-SELECTION.