diff --git a/regex.tal b/regex.tal
index c8583e9..1ea2849 100644
--- a/regex.tal
+++ b/regex.tal
@@ -408,6 +408,10 @@
 ( )
 ( the stack can be cleared using ;reset-stack, which resets )
 ( the stack pointers but does not zero out any memory. )
+( )
+( stack size is 4096 bytes here but is configurable. )
+( in some cases it could be very small but this will limit )
+( how many branches can be parsed and executed. )
 
 ( push 4 bytes onto the stack )
 @push4 ( str* regex* -> )
@@ -466,6 +470,10 @@
 ( the arena is used to allocate regex graph nodes, which are )
 ( dynamically-allocated as the regex string is parsed. once )
 ( a regex is no longer needed the arena may be reclaimed. )
+( )
+( arena size is 1024 bytes here but is configurable. )
+( smaller sizes would likely be fine but will limit the )
+( overall complexity of regexes to be parsed and executed. )
 
 ( reclaim all the memory used by the arena )
 @reset-arena ( -> )