add documentation

1 files changed, 4 insertions, 0 deletions

diff --git a/docs/env_variables.md b/docs/env_variables.md
index ebb7521e..49eadcaa 100644
--- a/docs/env_variables.md
+++ b/docs/env_variables.md
@@ -282,6 +282,10 @@ checks or alter some of the more exotic semantics of the tool:
     the target. This must be equal or larger than the size the target was
     compiled with.
 
+  - AFL_TESTCACHE_SIZE allows you to overrider the define in config.h for
+    TESTCASE_CACHE. Recommended values are 50-250MB - or more if your
+    fuzzing finds a huge amount of paths for large inputs.
+
   - Setting AFL_DISABLE_TRIM tells afl-fuzz to no trim test cases. This is
     usually a bad idea!