diff --git a/notes/forth/StacksAt6502.md b/notes/forth/StacksAt6502.md
index f13acfc..4aa1392 100644
--- a/notes/forth/StacksAt6502.md
+++ b/notes/forth/StacksAt6502.md
@@ -1,9 +1,13 @@
-# The Stacks
-
 _this is still a stub_
 
+# The Stacks
+
 _Charles Moore says 22 levels is enough for Forth._
 
+The R65F11, a 6502 clone with native Forth inside, uses 30 cells for return stack and 50 cells for parameter/data stack.
+
+The Forth Standarts recommends at least 24 cells for return stack and 36 cells for parameter/data stack.
+
 ## Back Stacks
 
 The 6502 have two peculiar pages, the zero page and stack page, both unique and with 256 bytes. All sub-routines calls (JSR) and returns (RTS) uses the stack page for 16-bit pointers, also the indirect indexed and indexed indirect modes uses page zero. Those are valuable resources.