Variable: next-screen-context-lines
next-screen-context-lines is a customizable variable defined in
window.c.
Value
2
Documentation
Number of lines of continuity when scrolling by screenfuls.
Probably introduced at or before Emacs version 28.1.
Source Code
// Defined in /usr/src/emacs/src/window.c
DEFVAR_INT ("next-screen-context-lines", next_screen_context_lines,
doc: /* Number of lines of continuity when scrolling by screenfuls. */);