The only Canvas I know of is the Terrain Canvas. Why that would be a problem when you render but not when you edit terrains I don't know.
If you are trying to render big, like over 4000 pixels Bryce won't let you. It doesn't say anything it just resets the image size and beeps. If you wan't bigger you usually have to render to disk. Is this the "all in one" you are referring to?