set status_channel [<text>]
This variable sets the format of the current channel name in the status bar of the current window. If the client is not on a channel in the current window, nothing is displayed.
This string is represented by %C in the STATUS_FORMAT string. The %C will expand to the current channel name in the STATUS_CHANNEL string before being placed in STATUS_FORMAT.
Customizing the channel name display in the status bar:
/set status_channel Chan: %C