Reserve Cost

Folder:

The folder to reserve the space in. You can use common folders like [ProgramFilesFolder], [INSTALLDIR], etc. You can right-click on the field and select Insert > Folder ID from the menu to see a list of available folders, or click on the Browse button to open the Folders dialog. Leave this field empty to refer to the folder that the component is installed to.

Reserve when run locally (bytes):

The number of bytes in the folder to reserve for the component when the component is set to be installed locally.

Reserve when run from source (bytes):

The number of bytes in the folder to reserve for the component when the component is set to be run from source.

More Information

MSDN Online: ReserveCost Table

WiX Help File: ReserveCost Element