{
{   This procedure  does  what  is neccessary to obtain an unused entry in the
{ member entry list for a particular set.  This may include allocating  a  new
{ member entry list, finding an unused entry in an existing member entry list,
{ or expanding an existing member entry list.
{
{       STP$GET_UNUSED_MEL_ENTRY (AST_INDEX, MEL_INDEX, STATUS)
{
{ AST_INDEX: (input) This parameter specifies the set for which a member entry
{       is  to  be found.  This is assumed to be a valid index into the active
{       set table.
{
{ MEL_INDEX: (output) This parameter returns the index  of  the  unused  entry
{       into the member entry list of the active set table entry.
{
{ STATUS: (output) This parameter returns the request status.
{
{       CONDITIONS: ose$mainframe_pageable_full
{
{       IDENTIFIER: stc$set_management_id
{
