diff -r 0c7e865fa7cb -r 5b067c681989 etc/settings
--- a/etc/settings	Wed Dec 30 11:21:54 2015 +0100
+++ b/etc/settings	Wed Dec 30 11:32:56 2015 +0100
@@ -14,7 +14,7 @@
 
 ISABELLE_SCALA_BUILD_OPTIONS="-encoding UTF-8 -nowarn -target:jvm-1.7 -Xmax-classfile-name 130"
 
-ISABELLE_JAVA_SYSTEM_OPTIONS="-server -XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled -Dfile.encoding=UTF-8 -Disabelle.threads=0"
+ISABELLE_JAVA_SYSTEM_OPTIONS="-server -XX:MinHeapFreeRatio=30 -XX:MaxHeapFreeRatio=60 -XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled -Dfile.encoding=UTF-8 -Disabelle.threads=0"
 
 classpath "$ISABELLE_HOME/lib/classes/Pure.jar"