tmux uses an alternate screen buffer which is the same height and width as the parent terminal.
Create And Attach To Sessions
To attach to an already created session:
$ tmux a -t <session_name>
Detach From A Session
To detach from a tmux session press:
while in the session. This will leave the session running in the background, so you can re-attach to it later.
Increase Scrollback Buffer Size
Add the following line to your ~/.tmux.conf file. This will allow you to retain more data (history) in the tmux scrollback buffer.
set -g history-limit 50000
Assign Key To Clear History
Add the following line to your ~/.tmux.conf file. This will allow you to press Ctrl-l to clear both the scrollback history and screen data at the same time.
bind -n C-l send-keys C-l \; clear-history
This will emulate similar behaviour to pressing Ctrl-K in bash.