diff -r 8e736ce4c6f4 -r 83459eb76fe3 etc/settings
--- a/etc/settings	Sun Sep 06 22:14:52 2015 +0200
+++ b/etc/settings	Tue Sep 08 11:44:15 2015 +0200
@@ -38,7 +38,15 @@
 ###
 
 ISABELLE_BUILD_OPTIONS=""
-ISABELLE_BUILD_JAVA_OPTIONS="-Djava.awt.headless=true -Xmx1024m -Xss1m"
+
+case "$ISABELLE_JAVA_PLATFORM" in
+  x86_64-*)
+    ISABELLE_BUILD_JAVA_OPTIONS="-Djava.awt.headless=true -Xms128m -Xmx1024m -Xss1m"
+    ;;
+  *)
+    ISABELLE_BUILD_JAVA_OPTIONS="-Djava.awt.headless=true -Xms512m -Xmx4096m -Xss4m"
+    ;;
+esac
 
 
 ###