PHP Calling ILERPG with varying length field

I am looking for an example where php calls an ilerpg service program
procedure which has a varying length field.

Zendsrv7 on IBMi V7R3

Currently this results in a java crash.

I have the following procedure interface;


d getDriversForOperator...
d PR
d pOperator 9a
d pJsonString like(jsonString_t)

d jsonString_t s 100000a varying
d template

And my php code snippet ...


$param[] = $conn->AddParameterChar('both', 9, 'pOperator',
'operator', $operator);
$param[] = $conn->AddParameterChar('both', 100000, 'pJsonString'
, 'jsonString', $json,4);

$ret = $conn->PgmCall('CDBSRV006', CDB_SW_LIBRARY, $param, NULL,
array('func'=>'GETDRIVERSFOROPERATOR'));

Any suggestions would be appreciated.

Thank you

Don Brown