Improve the max-specpdl-size doc string

* src/eval.c (syms_of_eval): Mention what "specpdl" means.

1 files changed, 13 insertions, 7 deletions

diff --git a/src/eval.c b/src/eval.c
index 66d34808f82..0f792b487ed 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -4311,13 +4311,19 @@ syms_of_eval (void)
 {
   DEFVAR_INT ("max-specpdl-size", max_specpdl_size,
               doc: /* Limit on number of Lisp variable bindings and `unwind-protect's.
-If Lisp code tries to increase the total number past this amount,
-an error is signaled.
-You can safely use a value considerably larger than the default value,
-if that proves inconveniently small.  However, if you increase it too far,
-Emacs could run out of memory trying to make the stack bigger.
-Note that this limit may be silently increased by the debugger
-if `debug-on-error' or `debug-on-quit' is set.  */);
+
+If Lisp code tries to use more bindings than this amount, an error is
+signaled.
+
+You can safely increase this variable substantially if the default
+value proves inconveniently small.  However, if you increase it too
+much, Emacs could run out of memory trying to make the stack bigger.
+Note that this limit may be silently increased by the debugger if
+`debug-on-error' or `debug-on-quit' is set.
+
+\"spec\" is short for \"special variables\", i.e., dynamically bound
+variables.  \"PDL\" is short for \"push-down list\", which is an old
+term for \"stack\".  */);
 
   DEFVAR_INT ("max-lisp-eval-depth", max_lisp_eval_depth,
               doc: /* Limit on depth in `eval', `apply' and `funcall' before error.