diff --git a/src/libintstructs/linked-list.c b/src/libintstructs/linked-list.c
index c83cc7bd9..a05e8dbf3 100644
--- a/src/libintstructs/linked-list.c
+++ b/src/libintstructs/linked-list.c
@@ -22,6 +22,7 @@
 #define ASSERT_LIST(list) \
 do { \
   linked_list_header *header = (linked_list_header *) list; \
+  JERRY_ASSERT (header); \
   JERRY_ASSERT (header->magic == LINKED_LIST_MAGIC); \
 } while (0);
 
diff --git a/src/libintstructs/linked-list.h b/src/libintstructs/linked-list.h
index 13c3bfcfb..8714120a1 100644
--- a/src/libintstructs/linked-list.h
+++ b/src/libintstructs/linked-list.h
@@ -32,6 +32,7 @@ __packed
 linked_list_header;
 
 typedef uint8_t* linked_list;
+#define null_list NULL
 
 linked_list linked_list_init (size_t);
 void linked_list_free (linked_list);
diff --git a/src/libintstructs/stack.h b/src/libintstructs/stack.h
index 22f12e0a0..a88edb66e 100644
--- a/src/libintstructs/stack.h
+++ b/src/libintstructs/stack.h
@@ -40,7 +40,7 @@
   STACK(temp_names, uint8_t, uint8_t)
 
   #define GLOBAL(NAME, VAR) \
-  NAME.data[VAR]
+  STACK_ELEMENT (NAME, VAR)
 
   #define MAX_TEMP_NAME() \
   GLOBAL(temp_names, max_temp_name)
@@ -54,7 +54,7 @@
   void
   parser_init (void)
   {
-    STACK_INIT(uint8_t, temp_names)
+    STACK_INIT(temp_names)
   }
 
   void
@@ -81,11 +81,11 @@ typedef struct \
 __packed \
 NAME##_stack;
 
-#define STACK_INIT(TYPE, NAME) \
+#define STACK_INIT(NAME) \
 do { \
-  NAME.blocks = linked_list_init (sizeof (TYPE)); \
+  NAME.blocks = linked_list_init (sizeof (NAME##_stack_value_type)); \
   NAME.current = NAME##_global_size; \
-  NAME.length = NAME.block_len = ((linked_list_header *) NAME.blocks)->block_size / sizeof (TYPE); \
+  NAME.length = NAME.block_len = ((linked_list_header *) NAME.blocks)->block_size / sizeof (NAME##_stack_value_type); \
 } while (0)
 
 #define STACK_FREE(NAME) \
diff --git a/src/libintstructs/tree.h b/src/libintstructs/tree.h
index 7995d70ca..4646b5467 100644
--- a/src/libintstructs/tree.h
+++ b/src/libintstructs/tree.h
@@ -23,6 +23,7 @@
 typedef struct tree_header
 {
   uint8_t magic;
+  uint8_t children_num;
   struct tree_header *parent;
   linked_list children;
 }
diff --git a/src/libjsparser/lexer.c b/src/libjsparser/lexer.c
index ad70a22ff..af44be341 100644
--- a/src/libjsparser/lexer.c
+++ b/src/libjsparser/lexer.c
@@ -1300,9 +1300,9 @@ lexer_init (const char *source, size_t source_size, bool show_opcodes)
   buffer_size = source_size;
   lexer_set_source (source);
 
-  STACK_INIT (lp_string, strings);
-  STACK_INIT (ecma_number_t, numbers);
-  STACK_INIT (idx_t, num_ids);
+  STACK_INIT (strings);
+  STACK_INIT (numbers);
+  STACK_INIT (num_ids);
 }
 
 void
diff --git a/src/libjsparser/parser.c b/src/libjsparser/parser.c
index 890fe366b..d49960cc1 100644
--- a/src/libjsparser/parser.c
+++ b/src/libjsparser/parser.c
@@ -25,6 +25,7 @@
 #include "deserializer.h"
 #include "opcodes-native-call.h"
 #include "parse-error.h"
+#include "scopes-tree.h"
 
 #define INVALID_VALUE 255
 #define INTRINSICS_COUNT 1
@@ -76,6 +77,14 @@ enum
 };
 STATIC_STACK (nestings, uint8_t, uint8_t)
 
+typedef scopes_tree* scopes_tree_p;
+
+enum
+{
+  scopes_global_size
+};
+STATIC_STACK (scopes, uint8_t, scopes_tree_p)
+
 enum
 {
   temp_name,
@@ -3592,6 +3601,10 @@ void
 parser_parse_program (void)
 {
   STACK_DECLARE_USAGE (IDX)
+  STACK_DECLARE_USAGE (scopes);
+
+  STACK_PUSH (scopes, scopes_tree_init (NULL));
+  serializer_set_scope (STACK_TOP (scopes));
 
   skip_newlines ();
   parse_source_element_list (true);
@@ -3601,8 +3614,14 @@ parser_parse_program (void)
   DUMP_OPCODE_1 (exitval, 0);
 
   serializer_adjust_strings ();
+  serializer_merge_scopes_into_bytecode ();
+
+  scopes_tree_free (STACK_TOP (scopes));
+  serializer_set_scope (NULL);
+  STACK_DROP (scopes, 1);
 
   STACK_CHECK_USAGE (IDX);
+  STACK_CHECK_USAGE (scopes);
 }
 
 void
@@ -3620,16 +3639,17 @@ parser_init (const char *source, size_t source_size, bool show_opcodes)
   serializer_dump_strings_and_nums (identifiers, lexer_get_strings_count (),
                                     lexer_get_nums (), lexer_get_nums_count ());
 
-  STACK_INIT (uint8_t, U8);
-  STACK_INIT (uint8_t, IDX);
-  STACK_INIT (uint8_t, nestings);
-  STACK_INIT (uint8_t, temp_names);
-  STACK_INIT (token, toks);
-  STACK_INIT (opcode_t, ops);
-  STACK_INIT (uint16_t, U16);
-  STACK_INIT (opcode_counter_t, rewritable_continue);
-  STACK_INIT (opcode_counter_t, rewritable_break);
-  STACK_INIT (locus, locs);
+  STACK_INIT (U8);
+  STACK_INIT (IDX);
+  STACK_INIT (nestings);
+  STACK_INIT (temp_names);
+  STACK_INIT (toks);
+  STACK_INIT (ops);
+  STACK_INIT (U16);
+  STACK_INIT (rewritable_continue);
+  STACK_INIT (rewritable_break);
+  STACK_INIT (locs);
+  STACK_INIT (scopes);
 
   HASH_INIT (intrinsics, 1);
 
@@ -3689,6 +3709,7 @@ parser_free (void)
   STACK_FREE (rewritable_continue);
   STACK_FREE (rewritable_break);
   STACK_FREE (locs);
+  STACK_FREE (scopes);
 
   HASH_FREE (intrinsics);
 
diff --git a/src/libjsparser/scopes-tree.c b/src/libjsparser/scopes-tree.c
new file mode 100644
index 000000000..84a2b59bb
--- /dev/null
+++ b/src/libjsparser/scopes-tree.c
@@ -0,0 +1,190 @@
+/* Copyright 2014 Samsung Electronics Co., Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "scopes-tree.h"
+#include "mem-heap.h"
+#include "jerry-libc.h"
+
+#define NAME_TO_ID(op) (__op__idx_##op)
+
+static void
+assert_tree (scopes_tree *t)
+{
+  JERRY_ASSERT (t != NULL);
+  JERRY_ASSERT (t->t.magic == TREE_MAGIC);
+}
+
+opcode_counter_t
+scopes_tree_opcodes_num (scopes_tree *t)
+{
+  assert_tree (t);
+  return t->opcodes_num;
+}
+
+void
+scopes_tree_add_opcode (scopes_tree *tree, opcode_t op)
+{
+  assert_tree (tree);
+  linked_list_set_element (tree->opcodes, sizeof (opcode_t), tree->opcodes_num++, &op);
+}
+
+void
+scopes_tree_set_opcode (scopes_tree *tree, opcode_counter_t oc, opcode_t op)
+{
+  assert_tree (tree);
+  JERRY_ASSERT (oc < tree->opcodes_num);
+  linked_list_set_element (tree->opcodes, sizeof (opcode_t), oc, &op);
+}
+
+void
+scopes_tree_set_opcodes_num (scopes_tree *tree, opcode_counter_t oc)
+{
+  assert_tree (tree);
+  JERRY_ASSERT (oc < tree->opcodes_num);
+  tree->opcodes_num = oc;
+}
+
+opcode_t
+scopes_tree_opcode (scopes_tree *tree, opcode_counter_t oc)
+{
+  assert_tree (tree);
+  JERRY_ASSERT (oc < tree->opcodes_num);
+  return *(opcode_t *) linked_list_element (tree->opcodes, sizeof (opcode_t), oc);
+}
+
+static opcode_counter_t
+count_opcodes_in_tree (scopes_tree *t)
+{
+  assert_tree (t);
+  opcode_counter_t res = t->opcodes_num;
+  for (uint8_t i = 0; i < t->t.children_num; i++)
+  {
+    res = (opcode_counter_t) (res
+                              + count_opcodes_in_tree ((scopes_tree *) linked_list_element (t->t.children,
+                                                                                            sizeof (scopes_tree *),
+                                                                                            i)));
+  }
+  return res;
+}
+
+static opcode_counter_t
+merge_subscopes (scopes_tree *tree, opcode_t *data)
+{
+  assert_tree (tree);
+  JERRY_ASSERT (data);
+  bool header = true;
+  opcode_counter_t opc_index, data_index;
+  for (opc_index = 0, data_index = 0; opc_index < tree->opcodes_num; opc_index++, data_index++)
+  {
+    opcode_t *op = (opcode_t *) linked_list_element (tree->opcodes, sizeof (opcode_t), opc_index);
+    JERRY_ASSERT (op);
+    switch (opc_index)
+    {
+      case 0:
+      {
+        JERRY_ASSERT (op->op_idx == NAME_TO_ID (reg_var_decl));
+        data[data_index] = *op;
+        break;
+      }
+      case 1:
+      {
+        JERRY_ASSERT (op->op_idx == NAME_TO_ID (nop) || op->op_idx == NAME_TO_ID (meta));
+        data[data_index] = *op;
+        break;
+      }
+      default:
+      {
+        if (op->op_idx == NAME_TO_ID (var_decl))
+        {
+          data[data_index] = *op;
+        }
+        else
+        {
+          header = false;
+        }
+      }
+    }
+    if (!header)
+    {
+      break;
+    }
+  }
+  for (uint8_t child_id = 0; child_id < tree->t.children_num; child_id++)
+  {
+    data_index = (opcode_counter_t) (data_index
+                                     + merge_subscopes ((scopes_tree *) linked_list_element (tree->t.children,
+                                                                                             sizeof (scopes_tree *),
+                                                                                             child_id),
+                                                        data + data_index));
+  }
+  for (; opc_index < tree->opcodes_num; opc_index++, data_index++)
+  {
+    opcode_t *op = (opcode_t *) linked_list_element (tree->opcodes, sizeof (opcode_t), opc_index);
+    data[data_index] = *op;
+  }
+  return data_index;
+}
+
+opcode_t *
+scopes_tree_raw_data (scopes_tree *tree, opcode_counter_t *num)
+{
+  assert_tree (tree);
+  opcode_counter_t res = count_opcodes_in_tree (tree);
+  size_t size = ((size_t) (res + 1) * sizeof (opcode_t)); // +1 for valgrind
+  opcode_t *opcodes = (opcode_t *) mem_heap_alloc_block (size, MEM_HEAP_ALLOC_LONG_TERM);
+  __memset (opcodes, 0, size);
+  opcode_counter_t merged = merge_subscopes (tree, opcodes);
+  JERRY_ASSERT (merged == res);
+  *num = res;
+  return opcodes;
+}
+
+scopes_tree *
+scopes_tree_init (scopes_tree *parent)
+{
+  scopes_tree *tree = (scopes_tree *) mem_heap_alloc_block (sizeof (scopes_tree), MEM_HEAP_ALLOC_SHORT_TERM);
+  __memset (tree, 0, sizeof (scopes_tree));
+  tree->t.magic = TREE_MAGIC;
+  tree->t.parent = (tree_header *) parent;
+  tree->t.children = null_list;
+  tree->t.children_num = 0;
+  if (parent != NULL)
+  {
+    if (parent->t.children_num == 0)
+    {
+      parent->t.children = linked_list_init (sizeof (scopes_tree *));
+    }
+    linked_list_set_element (parent->t.children, sizeof (scopes_tree *), parent->t.children_num++, tree);
+  }
+  tree->opcodes_num = 0;
+  tree->opcodes = linked_list_init (sizeof (opcode_t));
+  return tree;
+}
+
+void
+scopes_tree_free (scopes_tree *tree)
+{
+  assert_tree (tree);
+  for (uint8_t i = 0; i < tree->t.children_num; ++i)
+  {
+    scopes_tree_free ((scopes_tree *) linked_list_element (tree->t.children, sizeof (scopes_tree *), i));
+  }
+  if (tree->t.children_num != 0)
+  {
+    linked_list_free (tree->t.children);
+  }
+  linked_list_free (tree->opcodes);
+  mem_heap_free_block ((uint8_t *) tree);
+}
diff --git a/src/libjsparser/scopes-tree.h b/src/libjsparser/scopes-tree.h
new file mode 100644
index 000000000..7b282a6b3
--- /dev/null
+++ b/src/libjsparser/scopes-tree.h
@@ -0,0 +1,41 @@
+/* Copyright 2014 Samsung Electronics Co., Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SCOPES_TREE_H
+#define SCOPES_TREE_H
+
+#include "tree.h"
+#include "linked-list.h"
+#include "opcodes.h"
+
+typedef struct scopes_tree
+{
+  tree_header t;
+  opcode_counter_t opcodes_num;
+  linked_list opcodes;
+}
+__packed
+scopes_tree;
+
+scopes_tree *scopes_tree_init (scopes_tree *);
+void scopes_tree_free (scopes_tree *);
+opcode_counter_t scopes_tree_opcodes_num (scopes_tree *);
+void scopes_tree_add_opcode (scopes_tree *, opcode_t);
+void scopes_tree_set_opcode (scopes_tree *, opcode_counter_t, opcode_t);
+void scopes_tree_set_opcodes_num (scopes_tree *, opcode_counter_t);
+opcode_t scopes_tree_opcode (scopes_tree *, opcode_counter_t);
+opcode_t *scopes_tree_raw_data (scopes_tree *, opcode_counter_t *);
+
+#endif /* SCOPES_TREE_H */
diff --git a/src/liboptimizer/bytecode-data.h b/src/liboptimizer/bytecode-data.h
index c87cfb3d0..cccc1085c 100644
--- a/src/liboptimizer/bytecode-data.h
+++ b/src/liboptimizer/bytecode-data.h
@@ -20,6 +20,7 @@
 #include "stack.h"
 #include "jerry-libc.h"
 #include "lp-string.h"
+#include "scopes-tree.h"
 
 /* bytecode_data contains identifiers, string and num literals.
    Memory map if the following.
@@ -36,17 +37,15 @@ struct
 {
   uint8_t strs_count;
   uint8_t nums_count;
+  opcode_counter_t opcodes_count;
 
   const lp_string *strings;
   const ecma_number_t *nums;
+  const opcode_t *opcodes;
 }
 __packed
 bytecode_data;
 
-enum
-{
-  bytecode_opcodes_global_size
-};
-STACK (bytecode_opcodes, opcode_counter_t, opcode_t)
+scopes_tree *current_scope;
 
 #endif // BYTECODE_DATA_H
diff --git a/src/liboptimizer/deserializer.c b/src/liboptimizer/deserializer.c
index 1bb19fa16..a5dda7104 100644
--- a/src/liboptimizer/deserializer.c
+++ b/src/liboptimizer/deserializer.c
@@ -16,8 +16,6 @@
 #include "deserializer.h"
 #include "bytecode-data.h"
 
-static opcode_t *raw_bytecode;
-
 const ecma_char_t *
 deserialize_string_by_id (uint8_t id)
 {
@@ -42,18 +40,14 @@ deserialize_num_by_id (uint8_t id)
 const void *
 deserialize_bytecode (void)
 {
-  JERRY_ASSERT (STACK_SIZE (bytecode_opcodes) > 0);
-  JERRY_ASSERT (raw_bytecode == NULL);
-  STACK_CONVERT_TO_RAW_DATA (bytecode_opcodes, raw_bytecode);
-  return raw_bytecode;
+  JERRY_ASSERT (bytecode_data.opcodes != NULL);
+  return bytecode_data.opcodes;
 }
 
 opcode_t
 deserialize_opcode (opcode_counter_t oc)
 {
-  JERRY_ASSERT (STACK_SIZE (bytecode_opcodes) > 0);
-  JERRY_ASSERT (oc < STACK_SIZE (bytecode_opcodes));
-  return STACK_ELEMENT (bytecode_opcodes, oc);
+  return scopes_tree_opcode (current_scope, oc);
 }
 
 uint8_t
@@ -65,18 +59,12 @@ deserialize_min_temp (void)
 void
 deserializer_init (void)
 {
-  raw_bytecode = NULL;
-  STACK_INIT (opcode_t, bytecode_opcodes);
 }
 
 void
 deserializer_free (void)
 {
-  STACK_FREE (bytecode_opcodes);
-  if (raw_bytecode)
-  {
-    mem_heap_free_block ((uint8_t *) raw_bytecode);
-  }
   mem_heap_free_block ((uint8_t *) bytecode_data.strings);
   mem_heap_free_block ((uint8_t *) bytecode_data.nums);
+  mem_heap_free_block ((uint8_t *) bytecode_data.opcodes);
 }
diff --git a/src/liboptimizer/serializer.c b/src/liboptimizer/serializer.c
index 99e9bac5a..da22c8551 100644
--- a/src/liboptimizer/serializer.c
+++ b/src/liboptimizer/serializer.c
@@ -22,6 +22,19 @@
 
 static bool print_opcodes;
 
+void
+serializer_set_scope (scopes_tree *new_scope)
+{
+  current_scope = new_scope;
+}
+
+void
+serializer_merge_scopes_into_bytecode (void)
+{
+  bytecode_data.opcodes = scopes_tree_raw_data (current_scope, &bytecode_data.opcodes_count);
+}
+
+
 void
 serializer_dump_strings_and_nums (const lp_string strings[], uint8_t strs_count,
                                   const ecma_number_t nums[], uint8_t nums_count)
@@ -40,28 +53,26 @@ serializer_dump_strings_and_nums (const lp_string strings[], uint8_t strs_count,
 void
 serializer_dump_opcode (opcode_t opcode)
 {
-  JERRY_ASSERT (STACK_SIZE (bytecode_opcodes) < MAX_OPCODES);
+  JERRY_ASSERT (scopes_tree_opcodes_num (current_scope) < MAX_OPCODES);
 
   if (print_opcodes)
   {
-    pp_opcode (STACK_SIZE (bytecode_opcodes), opcode, false);
+    pp_opcode (scopes_tree_opcodes_num (current_scope), opcode, false);
   }
 
-  STACK_PUSH (bytecode_opcodes, opcode);
+  scopes_tree_add_opcode (current_scope, opcode);
 }
 
 void
 serializer_set_writing_position (opcode_counter_t oc)
 {
-  JERRY_ASSERT (oc < STACK_SIZE (bytecode_opcodes));
-  STACK_DROP (bytecode_opcodes, STACK_SIZE (bytecode_opcodes) - oc);
+  scopes_tree_set_opcodes_num (current_scope, oc);
 }
 
 void
 serializer_rewrite_opcode (const opcode_counter_t loc, opcode_t opcode)
 {
-  JERRY_ASSERT (loc < STACK_SIZE (bytecode_opcodes));
-  STACK_SET_ELEMENT (bytecode_opcodes, loc, opcode);
+  scopes_tree_set_opcode (current_scope, loc, opcode);
 
   if (print_opcodes)
   {
@@ -81,9 +92,9 @@ serializer_print_opcodes (void)
 
   __printf ("AFTER OPTIMIZER:\n");
 
-  for (loc = 0; loc < STACK_SIZE (bytecode_opcodes); loc++)
+  for (loc = 0; loc < bytecode_data.opcodes_count; loc++)
   {
-    pp_opcode (loc, STACK_ELEMENT (bytecode_opcodes, loc), false);
+    pp_opcode (loc, bytecode_data.opcodes[loc], false);
   }
 }
 
@@ -102,6 +113,7 @@ serializer_adjust_strings (void)
 void
 serializer_init (bool show_opcodes)
 {
+  current_scope = NULL;
   print_opcodes = show_opcodes;
 }
 
diff --git a/src/liboptimizer/serializer.h b/src/liboptimizer/serializer.h
index 9fdf6b30f..c31814e7e 100644
--- a/src/liboptimizer/serializer.h
+++ b/src/liboptimizer/serializer.h
@@ -20,10 +20,13 @@
 #include "opcodes.h"
 #include "interpreter.h"
 #include "lp-string.h"
+#include "scopes-tree.h"
 
 void serializer_init (bool show_opcodes);
 void serializer_dump_strings_and_nums (const lp_string *, uint8_t,
                                        const ecma_number_t *, uint8_t);
+void serializer_set_scope (scopes_tree *);
+void serializer_merge_scopes_into_bytecode (void);
 void serializer_dump_opcode (opcode_t);
 void serializer_set_writing_position (opcode_counter_t);
 void serializer_rewrite_opcode (const opcode_counter_t, opcode_t);