Share one case here I met: Someone modified the standard program SAPLSLVC_FULLSCREEN, so ALV output is not in full screen.
I found the screen 500 of the program SAPLSLVC_FULLSCREEN was modified, this can be seen in transaction SE80 -> Program -> SAPLSLVC_FULLSCREEN -> Screen -> 500 -> Layout:
Screen No. 0500 Modified/Active
the Attributes was change to:
Type Custom Control
Line 1 Column 1 Lngth 110 Height 19
so the ALV list will have length 110 and height 19. This can be changed it to the default value to length 240 and height 200 and then it will work.
But of cause you need the Access key as the program is a standard SAP program.
In case you met this knid of case. This will help then.