Building a tree recursively

I know someone out there must have done this before... I have a table: unit_link( parent_no integer, child_no integer... Each child can have children of it's own, for as many levels as necessary. I tried to build a recursive function call to build the tree as follows: function get_children(unit_no) declare child cursor for select child_no from unit_link where parent_no = unit_no foreach child into this_unit call get_children(this_unit)... By now you see the problem. On the second time through I get error -400 (Fetch attempted on unopen cursor). Tech support says that this is the way it is designed, you cannot re-use a cursor without first closing it. It seems to me that each recursive call should be within it's own stack and that re-using variables, cursors and the like should not be a problem, but... Is there another way to go about this w/o recursion? What methods have any of you used to solve similar problems? TIA BTW this is HP-UX 10.20 OnLine 7.22 4GL 6.04