mark-even-if-inactive

mark-even-if-inactive is a variable defined in `C source code'.
Its value is

t

Documentation:
Non-nil means you can use the mark even when inactive.
This option makes a difference in Transient Mark mode.
When the option is non-nil, deactivation of the mark
turns off region highlighting, but commands that use the mark
behave as if the mark were still active.

You can customize this variable.