1   data: 
 2     lt_callstack   type abap_callstack, 
 3     lt_e_callstack type sys_callst. 
 4  
 5   call function 'SYSTEM_CALLSTACK' 
 6     exporting 
 7       max_level          = 30 
 8     importing 
 9       callstack          = lt_callstack 
10       et_callstack       = lt_e_callstack .