ALTER SESSION SET plsql_optimize_level = 2

CREATE OR REPLACE PROCEDURE proc1 
IS 
   l_level   INTEGER; 
 
   PROCEDURE inline_proc1 
   IS 
   BEGIN 
      RAISE PROGRAM_ERROR; 
   EXCEPTION 
      WHEN OTHERS 
      THEN 
         DBMS_OUTPUT.put_line ('inline_proc1 handler'); 
 
         DBMS_OUTPUT.put_line (DBMS_UTILITY.format_error_backtrace); 
         RAISE; 
   END; 
BEGIN 
   SELECT plsql_optimize_level 
     INTO l_level 
     FROM user_plsql_object_settings 
    WHERE name = 'PROC1'; 
 
   DBMS_OUTPUT.put_line ('Opt level = ' || l_level); 
 
   inline_proc1; 
EXCEPTION 
   WHEN OTHERS 
   THEN 
      DBMS_OUTPUT.put_line ('inline handler'); 
 
      DBMS_OUTPUT.put_line (DBMS_UTILITY.format_error_backtrace); 
END;

BEGIN
   proc1;
END;

Now We Turn On Inlining

ALTER SESSION SET plsql_optimize_level = 3

Recompile PROC1

ALTER PROCEDURE proc1 COMPILE

The Backtrace Changes

BEGIN 
   proc1; 
END;

SELECT p.plsql_optimize_level
  FROM user_plsql_object_settings p
 WHERE name = 'PROC1'