diff --git a/src/rpn-branch.h b/src/rpn-branch.h
index 4610000..217cacb 100644
--- a/src/rpn-branch.h
+++ b/src/rpn-branch.h
@@ -72,7 +72,7 @@ int rpn_for(branch& myobj)
 	// store symbol with first value
     number num;
     num.set(myobj.farg1);
-    _heap->add(string(sym->_value), &num, num.size(), cmd_number);
+    _local_heap->add(string(sym->_value), &num, num.size(), cmd_number);
 
 	return myobj.arg1 + 1;
 }
@@ -99,7 +99,7 @@ int rpn_next(branch& myobj)
 		int type;
 		symbol* var = (symbol*)seq_obj(start_or_for->arg1);
 		// check symbol variable is a number, then increase
-        if (_heap->get(string(var->_value), obj, size, type) && (type == cmd_number))
+        if (_local_heap->get(string(var->_value), obj, size, type) && (type == cmd_number))
 			((number*)obj)->_value = myobj.farg1;
 	}
 
@@ -144,7 +144,7 @@ int rpn_step(branch& myobj)
 		int type;
 		symbol* var = (symbol*)seq_obj(start_or_for->arg1);
 		// check symbol variable is a number, then increase
-        if (_heap->get(string(var->_value), obj, size, type) && (type == cmd_number))
+        if (_local_heap->get(string(var->_value), obj, size, type) && (type == cmd_number))
 			((number*)obj)->_value = myobj.farg1;
 	}
 
diff --git a/src/rpn-program.h b/src/rpn-program.h
index 0fb7a15..54c21d7 100644
--- a/src/rpn-program.h
+++ b/src/rpn-program.h
@@ -12,7 +12,7 @@ void eval(void)
 		unsigned int size;
 		int type;
         string variable(((symbol*)_stack->back())->_value);
-		if (_heap->get(variable, obj, size, type))
+        if (_local_heap->get(variable, obj, size, type) || _global_heap->get(variable, obj, size, type))
 		{
             // if variable holds a program, run this program
             if (type == cmd_program)
@@ -50,7 +50,7 @@ void eval(void)
         if (program::parse(prog_text.c_str(), prog) == ret_ok)
         {
             // run it
-            prog.run(*_stack, *_heap);
+            prog.run(*_stack, *_global_heap);
         }
     }
 }
@@ -117,9 +117,10 @@ int inprog(branch& myobj)
     }
 
     // load variables
+    heap local_heap;
     for (unsigned int i = myobj.arg1 + count_symbols; i > myobj.arg1; i--)
     {
-        _heap->add(string(((symbol*)seq_obj(i))->_value), _stack->get_obj(0), _stack->get_len(0), _stack->get_type(0));
+        local_heap.add(string(((symbol*)seq_obj(i))->_value), _stack->get_obj(0), _stack->get_len(0), _stack->get_type(0));
         _stack->pop_back();
     }
 
@@ -131,7 +132,8 @@ int inprog(branch& myobj)
     if (program::parse(entry.c_str(), prog) == ret_ok)
     {
         // run it
-        prog.run(*_stack, *_heap);
+        prog.run(*_stack, *_global_heap, &local_heap);
+        //TODO here: _local_heap free
     }
 
     // point on next command
diff --git a/src/rpn-store.h b/src/rpn-store.h
index 7cdf7e6..5abca93 100644
--- a/src/rpn-store.h
+++ b/src/rpn-store.h
@@ -6,7 +6,7 @@ void sto(void)
 
     string name(((symbol*)_stack->get_obj(0))->_value);
     _stack->pop_back();
-	_heap->add(name, _stack->get_obj(0), _stack->get_len(0), _stack->get_type(0));
+    _global_heap->add(name, _stack->get_obj(0), _stack->get_len(0), _stack->get_type(0));
 	_stack->pop_back();
 }
 
@@ -20,7 +20,7 @@ void rcl(void)
 	unsigned int size;
 	int type;
     string variable(((symbol*)_stack->back())->_value);
-	if (_heap->get(variable, obj, size, type))
+    if (_local_heap->get(variable, obj, size, type) || _global_heap->get(variable, obj, size, type))
 	{
 		_stack->pop_back();
 		_stack->push_back(obj, size, type);
@@ -37,7 +37,7 @@ void auto_rcl(symbol* symb)
 		void* obj;
 		unsigned int size;
 		int type;
-        if (_heap->get(string(symb->_value), obj, size, type))
+        if (_local_heap->get(string(symb->_value), obj, size, type) || _global_heap->get(string(symb->_value), obj, size, type))
 			_stack->push_back(obj, size, type);
 		else
             _stack->push_back(symb, symb->size(), cmd_symbol);
@@ -52,10 +52,18 @@ void purge(void)
 	ARG_MUST_BE_OF_TYPE(0, cmd_symbol);
 
     string name(((symbol*)_stack->back())->_value);
-    if (!_heap->erase(name))
-		ERR_CONTEXT(ret_unknown_variable);
+    if (_local_heap->erase(name))
+    {
+        //TODO another error
+        ERR_CONTEXT(ret_bad_operand_type);
+    }
     else
-        _stack->pop_back();
+    {
+        if (!_global_heap->erase(name))
+            _stack->pop_back();
+        else
+            ERR_CONTEXT(ret_unknown_variable);
+    }
 }
 
 void vars(void)
@@ -65,9 +73,17 @@ void vars(void)
 	int type;
 	string name;
 
-	for (int i=0; i<(int)_heap->size(); i++)
+    for (int i=0; i<(int)_local_heap->size(); i++)
+    {
+        (void)_local_heap->get_by_index(i, name, (void*&)obj, size, type);
+        cout<<"local var "<<i+1<<": name '"<<name<<"', type "<<cmd_type_string[type]<<", value ";
+        obj->show();
+        cout<<endl;
+    }
+
+    for (int i=0; i<(int)_global_heap->size(); i++)
 	{
-		(void)_heap->get_by_index(i, name, (void*&)obj, size, type);
+        (void)_global_heap->get_by_index(i, name, (void*&)obj, size, type);
 		cout<<"var "<<i+1<<": name '"<<name<<"', type "<<cmd_type_string[type]<<", value ";
 		obj->show();
 		cout<<endl;
diff --git a/src/rpn-string.h b/src/rpn-string.h
index 7305402..4158ec9 100644
--- a/src/rpn-string.h
+++ b/src/rpn-string.h
@@ -29,6 +29,6 @@ void strout()
     if (program::parse(entry.c_str(), prog) == ret_ok)
 	{
 		// run it
-		prog.run(*_stack, *_heap);
+        prog.run(*_stack, *_global_heap);
 	}
 }
diff --git a/src/rpn.cpp b/src/rpn.cpp
index 55dfa30..08cfa76 100644
--- a/src/rpn.cpp
+++ b/src/rpn.cpp
@@ -361,14 +361,19 @@ public:
 	program() { }
 
 	// run this program
-	ret_value run(stack& stk, heap& hp)
+    ret_value run(stack& stk, heap& hp, heap* local_hp = NULL)
 	{
-		bool go_out = false;
+        heap local_heap;
+        bool go_out = false;
 		ret_value ret = ret_ok;
 		cmd_type_t type;
 
 		_stack = &stk;
-		_heap = &hp;
+        _global_heap = &hp;
+        if (local_hp != NULL)
+            _local_heap = local_hp;
+        else
+            _local_heap = &local_heap;
 		_err = ret_ok;
         _err_context = "";
 
@@ -688,7 +693,8 @@ private:
 	ret_value _err;
 	string _err_context;
 	stack* _stack;
-	heap* _heap;
+    heap* _global_heap;
+    heap* _local_heap;
 
 	// helpers for keywords implementation
 	floating_t getf()
@@ -770,8 +776,8 @@ static void apply_default(void)
 //
 int _tmain(int argc, _TCHAR* argv[])
 {
-	heap hp;
-	stack st;
+    heap global_heap;
+    stack global_stack;
 	int ret = 0;
 
 	// apply default configuration
@@ -790,10 +796,10 @@ int _tmain(int argc, _TCHAR* argv[])
 			else
 			{
 				// run it
-				if (prog.run(st, hp) == ret_good_bye)
+                if (prog.run(global_stack, global_heap) == ret_good_bye)
 					break;
 				else
-					program::show_stack(st);
+                    program::show_stack(global_stack);
 			}
 		}
 	}
@@ -818,8 +824,8 @@ int _tmain(int argc, _TCHAR* argv[])
 			string separator = "";
 
 			// run it
-			ret = prog.run(st, hp);
-			program::show_stack(st, separator);
+            ret = prog.run(global_stack, global_heap);
+            program::show_stack(global_stack, separator);
 		}
 	}