IWS and REST GET returning JSON with 'Header' and multiple 'Detail'

As currently coded, without options(*varsize) on orderEntries, the GET is returning the correct Header-type info and all 100 detail-type elements. I'd like to only return the number of detail rows that I actually have in the table. My attempt to address this is below, but I'm getting a RNF3701-Keyword not allowed for subfield definition.

Any thoughts? Thanks!

===========================
dcl-pr retrieve;
OrderNo char(20) const;
order likeds(orderInfo);
httpStatus int(10);
httpHeaders char(100) dim(10);
End-Pr;

===========================
dcl-ds orderInfo qualified template;
OrderNo char(20);
orderCreationTime char(20);
orderEntries_LENGTH int(10);
orderEntries likeds(orderEntriesInfo) Dim(100) options(*varsize);
end-ds;

Desired Output
==================
{
"OrderNo":"ABC123",
"orderCreationTime":"2019-01-01T23:28:56Z",
"source":"ECOMM" ,
"orderEntries":[
{
"ean":"123456789012345678",
"quantity":2,
"pickUpLocation":1,
"fulfillingLocation":2
},
{
"ean":"876543210987654321",
"quantity":1,
"pickUpLocation":1,
"fulfillingLocation":3
}
]
}