Calling Modal Dialog Boxes 

Calling a single screen is a special case of embedding a screen sequence. If you want to prevent the called screen from covering the current screen completely, you can use the CALL SCREEN statement with the STARTING AT and ENDING AT options:

CALL SCREEN <scrn>
     STARTING AT <X1> <Y1>
     ENDING AT   <X2> <Y2>.

This calls the screen number <scrn> as a modal dialog box. When the screen is displayed, the screen that had called it is visible but inactive. The STARTING AT and ENDING AT additions specify the top left-hand and bottom right-hand corners of the dialog box respectively. In the screen attributes of screen <scrn>, you must set the Modal dialog box attribute. This defines how the interface elements are positioned on the screen.