zOs/SQL/CATCOLS

with r (l, n) AS
(
    select varchar('', 1000), 0 from sysibm.sysDummyU
    union all select l || case when name = 'USERID'
                               then '' else ', ' || strip(name) end
            , n+1
        from r, sysibm.sysColumns where tbCreator = 'PTI'
               and tbName = 'PTRCQ_SAVED_RPTS' and colNo = n + 1
               and n < 999999
)
select max(l) from r