scroll-conservatively

scroll-conservatively is a variable defined in `C source code'.
Its value is

0

Documentation:
Scroll up to this many lines, to bring point back on screen.
If point moves off-screen, redisplay will scroll by up to
`scroll-conservatively' lines in order to bring point just barely
onto the screen again. If that cannot be done, then redisplay
recenters point as usual.

If the value is greater than 100, redisplay will never recenter point,
but will always scroll just enough text to bring point into view, even
if you move far away.

A value of zero means always recenter point if it moves off screen.

You can customize this variable.