Description:
------------
Probably I miss some point here but anyway - in the test script below bind data is passed to the query() function as an array from pre-created collection.
On each call memory consumption grows by pretty huge value (~65kB) even though oci_free_statement() is called.
The important conditions to reproduce:
  1. Bind array contains references. Without those I get
    639500
    639520

  2. PL/SQL script actually writes to one of bound variables. With the second (currently commented out) version I get
    639516
    657136


Test script:
---------------
function query($data) {
    global $conn;
    $stid = oci_parse($conn, 'begin select :a + :b into :b from dual; end;');
    //$stid = oci_parse($conn, 'declare j number; begin select :a + :b into j from dual; end;');

    oci_bind_by_name($stid, ':a', $data['a'], 100);
    oci_bind_by_name($stid, ':b', $data['b'], 100);

    oci_execute($stid);
    oci_free_statement($stid);
}

$conn = oci_connect('user', 'pass', 'dbref');
if (!$conn) {
    $e = oci_error();
    die($e['message']);
}

$data = array();
for($i = 0; $i < 1000; $i++) {
    $data[] = array(
        "a"   => 1,
        "b"   => 2
    );
}

print memory_get_usage() . "\n";
for($i = 0; $i < 100; $i++) {
    query(
        array(
            "a" => &$data[$i]["a"],
            "b" => &$data[$i]["b"]
        )
    );
}
print memory_get_usage() . "\n";

oci_close($conn);

Expected result:
----------------
639500
7202720

Actual result:
--------------
639500
639520 or nor far from this