1 files changed, 4 insertions, 0 deletions
diff --git a/docs/USAGE.md b/docs/USAGE.md
index ced076a9..5c67f0f8 100755
--- a/docs/USAGE.md
+++ b/docs/USAGE.md
@@ -321,3 +321,7 @@ Those variables are only valid inside a rcfile:
 #### BOX64_EXIT
  * 0 : Nothing special
  * 1 : Just exit, don't try to run the program
+
+#### BOX64_RESERVE_HIGH
+* 0 : Don't try to pe-reserve high memory (beyond 47bits) (Default)
+* 1 : Try to reserve (without allocating it) memory beyond 47bits (seems unstable)