SQL compund statement using FOR loop and writing JSON to the IFS

ifs_write_json.sql

begin
    declare cmd varchar(4096);
    declare comma varchar(1) default ''; 
    call qusrsys.ifs_write('/tmp/test.json'  , '[');  
    for vl as c1 cursor for select cusnum , lstnam from qiws.qcustcdt a do
        call qusrsys.ifs_append('/tmp/test.json'  , 
            comma concat  
            json_object (
                'customerNumber' : CUSNUM,
                'name' : LSTNAM
            )
        );
        set comma = ',';  
    end for;
    call qusrsys.ifs_append('/tmp/test.json'  , ']');  
end;

-- Which (for small file <32K ) can be written as:
call qusrsys.ifs_write('/tmp/test.json'  , 
    json_array((
        select 
            json_object (
                'customerNumber' : CUSNUM,
                'name' : LSTNAM
            )
        from qiws.qcustcdt
    ))
);