Do use the stacked version of the logo when the space is smaller to avoid shrinking the logo to an illegible size.
Do use the stacked version for mobile formats to maintain legibility.
Crowding & Overflow
Don't crowd mobile formats or overflow containers with full logo.
Don't shrink the logo within mobile formats to get it to fit while loosing legibility.
Do use the stacked logo as it is better suited for mobile layouts and narror vertical containers.