If alternate ACS routines are to be traced (the third positional parameter on ACSTRACE= is specified), the optional JCL keyword SCDSNAME= indicates which SCDS contains the alternate set of ACS routines to be traced. The format of the SCDSNAME keyword is:
SCDSNAME=dsn
where 'dsn' is the dataset name (not the DD name) of one of the //SCDSxx datasets allo- cated to the DIF started task. If the dataset is not allocated to the DIF started task, message ACC80210-I ** SCDS DD NOT FOUND IN DIF is issued and only the active ACS rou- tines are traced. SCDSNAME may specify the dataset allocated to the //SCDS DD state- ment or any of the //SCDSxx DD statements. If SCDSNAME= is not specified but alternate ACS tracing is required, then the dataset allocated to the //SCDS DD is used.