diff --git a/jerry-core/api/external-context-helpers.c b/jerry-core/api/external-context-helpers.c
index e5f9fc260bd797b572e42a8ceafc94ab2bdfd22a..15b7258eecdc81260f2a799bc6a874900119d26f 100755
--- a/jerry-core/api/external-context-helpers.c
+++ b/jerry-core/api/external-context-helpers.c
@@ -34,7 +34,7 @@ static void * bms_task_context_alloc (size_t total_size, void *cb_data_p)
  */
 void bms_task_context_init (void)
 {
-  jerry_context_t * bms_task_context = jerry_create_context (GT_TASK_HEAP_SIZE * CONVERTION_RATIO,
+  jerry_context_t * bms_task_context = jerry_create_context (BMS_TASK_HEAP_SIZE * CONVERTION_RATIO,
                                         bms_task_context_alloc, NULL);
 
   jerry_port_default_set_current_context (bms_task_context);
@@ -60,7 +60,7 @@ static void * js_task_context_alloc (size_t total_size, void *cb_data_p)
  */
 void js_task_context_init (void)
 {
-  jerry_context_t * js_task_context = jerry_create_context (GT_TASK_HEAP_SIZE * CONVERTION_RATIO,
+  jerry_context_t * js_task_context = jerry_create_context (JS_TASK_HEAP_SIZE * CONVERTION_RATIO,
                                         js_task_context_alloc, NULL);
 
   jerry_port_default_set_current_context (js_task_context);
diff --git a/jerry-port/config-jupiter.h b/jerry-port/config-jupiter.h
index c9f47edbb165d9ef17e99e79f318fa24569ac434..1bc8f281ed82a5a65160cbd178b291b6ca6089db 100755
--- a/jerry-port/config-jupiter.h
+++ b/jerry-port/config-jupiter.h
@@ -15,14 +15,23 @@
 #define INPUTJS_BUFFER_SIZE (32 * 1024)
 #define SNAPSHOT_BUFFER_SIZE (24 * 1024)
 #define CONVERTION_RATIO (1024)
+#define CONTEXT_SIZE_FOR_TASK (3)
 
-#define GT_TASK_HEAP_SIZE (48)
-#define BMS_TASK_FOR_CONTEXT_SIZE (3)
-#define BMS_TASK_CONTEXT_AND_HEAP_SIZE (GT_TASK_HEAP_SIZE + BMS_TASK_FOR_CONTEXT_SIZE)
+#ifndef BMS_TASK_HEAP_SIZE
+#define BMS_TASK_HEAP_SIZE (48)
+#endif /* BMS_TASK_HEAP_SIZE */
 
-#define JS_TASK_CONTEXT_AND_HEAP_SIZE_BYTE (51416)  // >= 51400 + 8
+#define BMS_TASK_CONTEXT_AND_HEAP_SIZE (BMS_TASK_HEAP_SIZE + CONTEXT_SIZE_FOR_TASK)
 
-#endif // JERRY_IAR_JUPITER
-#endif // JERRY_FOR_IAR_CONFIG
+#ifndef JS_TASK_HEAP_SIZE
+#define JS_TASK_HEAP_SIZE (64)
+#endif /* JS_TASK_HEAP_SIZE */
+
+// >= 51400 + (64-48) * 1024 + 8
+#define JS_TASK_CONTEXT_AND_HEAP_SIZE_BYTE (JS_TASK_HEAP_SIZE * CONVERTION_RATIO + 2248 + 16)
+
+#endif /* JERRY_IAR_JUPITER */
+
+#endif /* JERRY_FOR_IAR_CONFIG */
 
 #endif // CONFIG_JUPITER_H