>>>>Try PROGRAM() or ASTACKINFO()
>>
>>Only SWAG: as I did not measure time needed for duplicate call in program(program(-1)-1) vs. astackinfo() filling array plus array access. I'd guess program(program(-1)-1) to be faster and to show less variation of runtime depending on stack level. When debugging or logging program state in depth: after astackinfo() you can obtain more info with ease as structure has been filled - but if you are after simple "who called me" info mentioned in yourOP to log semi automatically always hooked into your SQL operations I'd opt for function(s) call I guess to fulfill needs more KISS than others, here program(program(-1)-1).
>>
>>my 0.02 €
>>thomas
>
>A follow-up question please. So far, my test shows that program(program(-1)-1) will give what I am looking for.
>Since I write this value to a log file, I want to be sure that it is always a string, not a numeric value. Can you think of a case where program(program(-1)-1) will give a numeric value?
>Thanks.

According to the online help PRORRAM() returns a string value, except in the case where the optional parameter is -1 where PROGRAM() will return the current program level.

You may find occasions where a more complete "traceback" in an error log list may be useful than simply just a reference to the program in which the error was triggered (as it may provide contextual information -- i.e. "how you got here" information).