src/Pure/Thy/sessions.scala

 
     override def toString: String = "Store(output_dir = " + output_dir.expand + ")"
 
     def prepare_output() { Isabelle_System.mkdirs(output_dir + Path.basic("log")) }
 
+    def output_heap(name: String): Path = output_dir + Path.basic(name)
     def output_log(name: String): Path = output_dir + log(name)
     def output_log_gz(name: String): Path = output_dir + log_gz(name)
 
     def open_output_database(name: String): SQL.Database =
       SQLite.open_database(output_dir + database(name))