Das API ist schon das Richtige!
Für ILE musst du nur in das richtige Feld des Callstack-Entries schauen:

Statement identifiers. The high-level language statement identifier. If this field contains the character representation of a number, the number is right-adjusted in the field and padded on the left with zeros (for example, '0000000246'). If the call stack entry is for an integrated language environment (ILE) procedure, more than one statement identifier may exist because of the compilers used for ILE languages.