Index: trunk/psphot/src/psphotStackArguments.c
===================================================================
--- trunk/psphot/src/psphotStackArguments.c	(revision 34282)
+++ trunk/psphot/src/psphotStackArguments.c	(revision 38384)
@@ -31,4 +31,11 @@
     // these options override the PSPHOT recipe values loaded from recipe files
     psMetadata *options = pmConfigRecipeOptions (config, PSPHOT_RECIPE);
+
+    bool updateMode = false;
+    if ((N = psArgumentGet (argc, argv, "-updatemode"))) {
+        psArgumentRemove (N, &argc, argv);
+        updateMode = true;
+    }
+    psMetadataAddBool(config->arguments, PS_LIST_TAIL, "PSPHOT.STACK.UPDATEMODE", 0, "update mode flag", updateMode);
 
     // visual : interactive display mode