The MaximumRowCount is stored in the Windows 8 registry and allows you to configure the number of app rows
The new Windows 8 has come up with an enticing and intuitive Start Menu, now like a Metro showing on the entire screen. This has added a new graphical interface to Windows 8 in order to operate it in a more user-friendly manner. Windows 8 automatically detects your current screen resolution and adjusts the Rows in Metro Screen accordingly. Be default, the value is 3 to 5 rows. In case you want to change the number of rows, here is how you can do it.
1.This is how the Metro Menu on my screen looks like before any changes
2. Execute Run and type in regedit and press Enter
3. Go to the following Key:
You should see the Layout_MaximumRowCount key on the right hand side. In case you do not see it, you should be able to create it. Right click anywhere in empty space, click New and Dword (32-bit) value. Once the key has been generated, rename it as Layout_MaximumRowCount
Type in the number of rows that you want and press Enter
Once you are done, just sign out and in to witness the changes.