--- old/src/hotspot/share/gc/z/z_globals.hpp	2020-02-17 13:00:58.519850800 +0900
+++ new/src/hotspot/share/gc/z/z_globals.hpp	2020-02-17 13:00:58.228533300 +0900
@@ -58,6 +58,10 @@
           "Uncommit memory if it has been unused for the specified "        \
           "amount of time (in seconds)")                                    \
                                                                             \
+  experimental(bool, ZAllowHeapOnFileSystem, false,                         \
+          "Allow to use filesystem as Java heap backing storage "           \
+          "specified by -XX:AllocateHeapAt")                                \
+                                                                            \
   diagnostic(uint, ZStatisticsInterval, 10,                                 \
           "Time between statistics print outs (in seconds)")                \
           range(1, (uint)-1)                                                \