diff --git a/checkin_notes b/checkin_notes
index 0a664840c8..c7f31b6633 100755
--- a/checkin_notes
+++ b/checkin_notes
@@ -1391,3 +1391,9 @@ David  30 Jan 2007
     tools/
         backend_lib.C,h
         create_work.C
+
+David  30 Jan 2007
+    - Unix: when increasing stack size for apps, don't exceed 500 MB
+
+    client/
+        app_start.C
diff --git a/client/app_start.C b/client/app_start.C
index 85adaba5ad..0d3991c407 100644
--- a/client/app_start.C
+++ b/client/app_start.C
@@ -617,7 +617,11 @@ int ACTIVE_TASK::start(bool first_time) {
         //
         struct rlimit rlim;
         getrlimit(RLIMIT_STACK, &rlim);
-        rlim.rlim_cur = rlim.rlim_max;
+        if (rlim.rlim_max == RLIM_INFINITY || rlim.rlim_max > 500000000) {
+            rlim.rlim_cur = 500000000; // 500 MB max
+        } else {
+            rlim.rlim_cur = rlim.rlim_max;
+        }
         setrlimit(RLIMIT_STACK, &rlim);
 
         // hook up stderr to a specially-named file