The navigation stack is the portion of the ServiceNow suite of applications that determines where a user is redirected after the update of a record.

An administrator can cause page references to be manually inserted into the navigation stack when a link in the Navigation Page is clicked. This is done by modifying a module definition to include an argument of sysparm_stack with a string value equal to the URL reference to the page to be inserted into the stack. The administrator can also override the redirection determined by the stack by creating a business rule or editing an existing one to include gs.setRedirect("http://redirect_page.com").

Operating parameters of the navigation stack

The navigation stack can be thought of a user's navigation history in the instance. It is updated every time a user views a new page. The navigation stack is referenced when users press the page back button. It is also referenced when a user submits or updates a record, at which point users are redirected to their last page in the navigation stack.
Figure 1. Back and Submit or Update
Actions that invoke the navigation stack

Inserting pages to the navigation stack

The administrator can insert page references manually into the navigation stack when a link in the navigation page is clicked. The module definition is modified to include an argument of sysparm_stack with a string value equal to the URL reference to the page to insert into the stack. The following image shows the system definition for the Incident > Create New module. By passing an argument of "sysparm_stack=incident_list.do", the list view of incidents (incident_list.do) is added to the stack. After submitting an incident, the user is directed to this page.
Figure 2. Sysparm stack example
Argument in a module link

Overriding the redirection behaviors of the navigation stack with onEvent business rules

The redirection behaviors that occur as a result of navigation stack behaviors can be overridden using onEvent business rules. This override is performed by using the function gs.setRedirect. Doing so overrides the redirection as determined by the navigation stack, when the specified event occurs. The function gs.setRedirect takes a string argument that is a URL for the page that the user is redirected to. This URL can be external, for example: gs.setRedirect('http://www.google.com').