  The spectrum of superstring theory on the $AdS_5 \times S_5$ Ramond-Ramond
background in tensionless limit contains integer and half-integer higher-spin
fields subject at most to two-rows Young tableaux $Y(s_1,s_2)$. We review the
details of a gauge-invariant Lagrangian description of such massive and
massless higher-spin fields in anti-de-Sitter spaces with arbitrary dimensions.
The procedure is based on the construction of Verma modules, its oscillator
realizations and of a BFV-BRST operator for non-linear algebras encoding
unitary irreducible representations of AdS group.
