code below, works as expected:
/*--------------------------------------------------*/
$query = "SELECT * FROM USERS";
$conn = OCILogon("username", "passwd", "db");
$stmt = OCIParse($conn, $query);
OCIExecute($stmt);
while (OCIFetchInto($stmt, &$row, OCI_ASSOC)) {
	echo $row["LASTNAME"] . ", " . $row["FIRSTNAME"] . "<br>";
}
OCIFreeStatement($stmt);
OCILogoff($conn);
/*--------------------------------------------------*/
HOWEVER...

THIS code below, does not:

/*--------------------------------------------------*/
function getusers() {
	$query = "SELECT * FROM USERS";
	$conn = OCILogon("username", "passwd", "db");
	$stmt = OCIParse($conn, $query);
	OCIExecute($stmt);
	while (OCIFetchInto($stmt, &$row, OCI_ASSOC)) {
		echo $row["LASTNAME"] . ", " . $row["FIRSTNAME"] . "<br>";
	}
	OCIFreeStatement($stmt);
	OCILogoff($conn);
}
/*--------------------------------------------------*/

After tearing my hair out for an hour, i tried THIS:

/*--------------------------------------------------*/
function getusers() {
	$query = "SELECT * FROM USERS";
	$conn = OCILogon("username", "passwd", "db");
	$stmt = OCIParse($conn, $query);
	OCIExecute($stmt);
	while (OCIFetchInto($stmt, &$row, OCI_ASSOC)) {
		echo $row[0] . ", " . $row[1] . "<br>";
	}
	OCIFreeStatement($stmt);
	OCILogoff($conn);
}
/*--------------------------------------------------*/

REGARDLESS of using OCI_ASSOC or OCI_NUM, the OCIFetchInto called from within the FUNCTION returned an enumerative 0-based array into $row, whereas the OCIFetchInto called in the ordinary code (using OCI_ASSOC) returned an associative array into $row.