up
The up command selects and prints the function that called this one, or
  the function specified by the frame number in the call stack.
Syntax
up [frames]
- frames says how many frames up to go in the stack. The default is 1.
 
Usage
The up command moves towards the outermost frame, to frames that have existed
    longer. To print the function that called the current function, use the up
    command without an argument.
See stack frames for a brief description of frames.
Example
(fgldb) up
#1 main() at customain.4gl:14 
14    CALL query_cust()
(fgldb)