I have added a menu item in main-menu using following code
$item = array(
'menu_name' => 'main-menu',
'link_path' => 'my-profile',
'link_title' => 'Services',
'module' => 'menu',
'weight' => 0,
);
menu_link_save($item);
menu_cache_clear_all();
this code is placed in lcp_theme function, lcp is custom module and is working properly except this added menu item. I cant see this menu at top of the site in main menu.
As per the documentation I can use this function anywhere in module.