IBM 3270 Manual page 26

To look at another window:
1.
Press the Jump key.
The next window in alphabetical order will
appear. It becomes the "active" window. The
windows are kept in alphabetical order by
their short names. When the windows fill the
screen you can see the names of the windows.
The names appear in the border.
2. To go to the next window in order, press the
Jump key again.
3. To get back to the first window again, keep
pressing the Jump key.
Now, you know how to find and select your
windows.
Chapter 2. Selecting and Using Your Windows 2-7