diff --git a/src/sos/executor_utils.py b/src/sos/executor_utils.py
index d0277c37a..de913964e 100644
--- a/src/sos/executor_utils.py
+++ b/src/sos/executor_utils.py
@@ -231,7 +231,6 @@ def create_task(global_def, task_stmt, task_params):
                 task_tags.append(tag)
 
     # save task to a file
-    task_vars['__task_vars__'] = copy.copy(task_vars)
     taskdef = TaskParams(
         name='{} (index={})'.format(
             env.sos_dict['step_name'], env.sos_dict['_index']),
diff --git a/src/sos/step_executor.py b/src/sos/step_executor.py
index 367de5e42..522bbdd54 100755
--- a/src/sos/step_executor.py
+++ b/src/sos/step_executor.py
@@ -107,7 +107,7 @@ def get_job(self, all_tasks=False):
             for idx, (task_id, taskdef, _) in slot:
                 master.push(task_id, taskdef)
             ids.append(master.ID)
-            TaskFile(master.ID).save(master)
+            TaskFile(master.ID).save(master.finalize())
             env.signature_push_socket.send_pyobj(['workflow', 'task', master.ID,
                                   f"{{'creation_time': {time.time()}}}"])
         self._unsubmitted_slots = []
@@ -146,7 +146,7 @@ def get_job(self, all_tasks=False):
                 master.push(task_id, taskdef)
             # the last piece
             if master is not None:
-                TaskFile(master.ID).save(master)
+                TaskFile(master.ID).save(master.finalize())
                 env.signature_push_socket.send_pyobj(['workflow', 'task', master.ID,
                                           f"{{'creation_time': {time.time()}}}"])
                 ids.append(master.ID)
diff --git a/src/sos/task_executor.py b/src/sos/task_executor.py
index 74393b34b..db2b5b941 100644
--- a/src/sos/task_executor.py
+++ b/src/sos/task_executor.py
@@ -238,6 +238,8 @@ def copy_out_and_err(result):
             p = Pool(params.num_workers)
             results = []
             for tid, tdef in params.task_stack:
+                if hasattr(params, 'common_dict'):
+                    tdef.sos_dict.update(params.common_dict)
                 results.append(p.apply_async(_execute_task,
                                              ((tid, tdef, {tid: sig_content.get(tid, {})}), verbosity, runmode,
                                               sigmode, None, None), callback=copy_out_and_err))
@@ -257,6 +259,8 @@ def copy_out_and_err(result):
         else:
             results = []
             for tid, tdef in params.task_stack:
+                if hasattr(params, 'common_dict'):
+                    tdef.sos_dict.update(params.common_dict)
                 # no monitor process for subtasks
                 res = _execute_task((tid, tdef, {tid: sig_content.get(tid, {})}), verbosity=verbosity, runmode=runmode,
                                     sigmode=sigmode, monitor_interval=None, resource_monitor_interval=None)
diff --git a/src/sos/tasks.py b/src/sos/tasks.py
index 559d59617..e75a590f6 100644
--- a/src/sos/tasks.py
+++ b/src/sos/tasks.py
@@ -132,6 +132,23 @@ def push(self, task_id, params):
         self.ID = f'M{len(self.task_stack)}_{self.task_stack[0][0]}'
         self.name = self.ID
 
+    def finalize(self):
+        if not self.task_stack:
+            return
+        common_dict = None
+        common_keys = set()
+        for id, params in self.task_stack:
+            if common_dict is None:
+                common_dict = params.sos_dict
+                common_keys = set(params.sos_dict.keys())
+            else:
+                common_keys = {key for key in common_keys if key in params.sos_dict and common_dict[key] == params.sos_dict[key]}
+            if not common_keys:
+                break
+        self.common_dict = {x:common_dict[x] for x in common_keys}
+        for id, params in self.task_stack:
+            params.sos_dict = {k:v for k,v in params.sos_dict.items() if k not in common_keys}
+        return self
 
 class TaskStatus(Enum):
     new = 0