This is typically a code used by Chase Bank (possibly others) indicating that they are pending a credit to your account. The credit amount associated with the “HOLD REL MEM CR” status is usually associated with recent a large deposit.
They also usually allow a (small) portion of the funds to be immediately available.
If you use Chase Bank and want more details, call their Deposit Hold Team at 1-877-691-808 (Press Option 1).