reef-patch

diff --git a/lang/java/reef-common/src/main/java/org/apache/reef/runtime/common/launch/JavaLaunchCommandBuilder.java b/lang/java/reef-common/src/main/java/org/apache/reef/runtime/common/launch/JavaLaunchCommandBuilder.java
index 8084068..534fa68 100644
--- a/lang/java/reef-common/src/main/java/org/apache/reef/runtime/common/launch/JavaLaunchCommandBuilder.java
+++ b/lang/java/reef-common/src/main/java/org/apache/reef/runtime/common/launch/JavaLaunchCommandBuilder.java
@@ -55,7 +55,8 @@ public final class JavaLaunchCommandBuilder implements LaunchCommandBuilder {
       add("-XX:PermSize=128m");
       add("-XX:MaxPermSize=128m");
       // Set Xmx based on am memory size
-      add("-Xmx" + megaBytes + "m");
+      add("-Xmx" + (megaBytes - 4) + "m");
+      add("-Xss4m");
 
       if ((assertionsEnabled != null && assertionsEnabled)
           || EnvironmentUtils.areAssertionsEnabled()) {