Extend ALV size to max screen' height/width without hidding susbcreen

Hi experts,

Actually, i have a screen like this :

Both frame above are subscreen and below, it's a custom container.

Question : How can i display full screen size height/width my ALV without going over the two subscreens above (because it is what is happening right now when i try to use the "EXTENSION" attribut of my CL_GUI_DOCKING_CONTAINER - With combo DOCK_AT_TOP/LEFT etc.).

NB : My subscreens must be dislpayed all the time.

I can't use split container because i can't put subscreen in split container soooo...It's not a life and death question but it's been bothering each time i open this custom transaction...

Thanks a lot for your help.

Alexandre