Stack items
Stack items are form elements used to define a stack-based layout in a
        STACK container.
To define a stacked layout within a STACK container, leaf stack items (typically, form fields, labels, buttons)
are specified inside grouping stack items such as GROUP or TABLE.
The example shows a stack-based form definition with a 
GROUP stack item
containing two EDIT stack
items:LAYOUT
 STACK
   GROUP g1
       EDIT customer.cust_num, NOENTRY;
       EDIT customer.cust_name, REQUIRED;
   END
 END
END