How to unfreeze after accidentally pressing Ctrl-S in a terminal?

It's a situation that has happened quite often to me: after I press (with a different intention) Ctrl-S in a terminal, the interaction (input or output) with it is frozen. It's probably a kind of "scroll lock" or whatever. How do I unfreeze the terminal after this? (This time, I have been working with apt-shell inside a bash inside urxvt--not sure which of them is responsible for the special handl

[masterq]

"stty -ixon" C-sを抑制する