Index: kernel/generic/include/config.h
===================================================================
--- kernel/generic/include/config.h	(revision 3ac5086e0b5b6d93c26f2b1c150344366e5478e8)
+++ kernel/generic/include/config.h	(revision cb10bc9a558169f21c11cf80a9da8706c68bcdc3)
@@ -44,4 +44,6 @@
 #define STACK_FRAMES  TWO_FRAMES
 #define STACK_SIZE    ((1 << STACK_FRAMES) << PAGE_WIDTH)
+
+#define STACK_SIZE_USER	(1 * 1024 * 1024)
 
 #define CONFIG_INIT_TASKS        32
Index: kernel/generic/include/mm/as.h
===================================================================
--- kernel/generic/include/mm/as.h	(revision 3ac5086e0b5b6d93c26f2b1c150344366e5478e8)
+++ kernel/generic/include/mm/as.h	(revision cb10bc9a558169f21c11cf80a9da8706c68bcdc3)
@@ -65,10 +65,4 @@
 #define USER_ADDRESS_SPACE_END      USER_ADDRESS_SPACE_END_ARCH
 
-#ifdef USTACK_ADDRESS_ARCH
-	#define USTACK_ADDRESS  USTACK_ADDRESS_ARCH
-#else
-	#define USTACK_ADDRESS  (USER_ADDRESS_SPACE_END - (STACK_SIZE - 1))
-#endif
-
 /** Kernel address space. */
 #define FLAG_AS_KERNEL  (1 << 0)
@@ -78,12 +72,15 @@
 #define AS_AREA_ATTR_PARTIAL  1  /**< Not fully initialized area. */
 
+/** The page fault was resolved by as_page_fault(). */
+#define AS_PF_OK     0 
+
+/** The page fault was caused by memcpy_from_uspace() or memcpy_to_uspace(). */
+#define AS_PF_DEFER  1
+
 /** The page fault was not resolved by as_page_fault(). */
-#define AS_PF_FAULT  0
-
-/** The page fault was resolved by as_page_fault(). */
-#define AS_PF_OK  1
-
-/** The page fault was caused by memcpy_from_uspace() or memcpy_to_uspace(). */
-#define AS_PF_DEFER  2
+#define AS_PF_FAULT  2
+
+/** The page fault was not resolved by as_page_fault(). Non-verbose version. */
+#define AS_PF_SILENT 3
 
 /** Address space structure.
@@ -228,4 +225,7 @@
 	void (* destroy)(as_area_t *);
 
+	bool (* is_resizable)(as_area_t *);
+	bool (* is_shareable)(as_area_t *);
+
 	int (* page_fault)(as_area_t *, uintptr_t, pf_access_t);
 	void (* frame_free)(as_area_t *, uintptr_t, uintptr_t);