diff --git a/packages/app.spec.sql b/packages/app.spec.sql
index f70da84..f99ad13 100644
--- a/packages/app.spec.sql
+++ b/packages/app.spec.sql
@@ -29,10 +29,11 @@ CREATE OR REPLACE PACKAGE app AS
      *
      */
 
+    --
+    core_alias                  CONSTANT VARCHAR2(30)           := 'CORE';
+    --
     schema_owner                CONSTANT VARCHAR2(30)           := 'CORE';
     schema_apex                 CONSTANT VARCHAR2(30)           := 'APEX_210100';
-    --
-    core_app_id                 CONSTANT sessions.app_id%TYPE   := 770;  -- for sharing pages between apps
 
     -- code for app exception
     app_exception_code          CONSTANT PLS_INTEGER            := -20000;
@@ -124,7 +125,8 @@ CREATE OR REPLACE PACKAGE app AS
     -- Return app_id for CORE application
     --
     FUNCTION get_core_app_id
-    RETURN sessions.app_id%TYPE;
+    RETURN sessions.app_id%TYPE
+    RESULT_CACHE;
 
 
 
diff --git a/packages/app.sql b/packages/app.sql
index 880ab25..c04ffde 100644
--- a/packages/app.sql
+++ b/packages/app.sql
@@ -46,9 +46,18 @@ CREATE OR REPLACE PACKAGE BODY app AS
 
     FUNCTION get_core_app_id
     RETURN sessions.app_id%TYPE
+    RESULT_CACHE
     AS
+        out_id                  apex_applications.application_id%TYPE;
     BEGIN
-        RETURN COALESCE(app.core_app_id, 0);
+        SELECT a.application_id INTO out_id
+        FROM apex_applications a
+        WHERE a.alias = app.core_alias;
+        --
+        RETURN out_id;
+    EXCEPTION
+    WHEN NO_DATA_FOUND THEN
+        app.raise_error('CORE_MISSING');
     END;