  We discuss semiclassical quantization of circular pulsating strings in AdS3 x
S3 background with and without the Neveu-Schwarz- Neveu-Schwarz (NS-NS) flux.
We find the equations of motion corresponding to the quadratic action in
bosonic sector in terms of scalar quantities and invariants of the geometry.
The general equations for studying physical perturbations along the string in
an arbitrary curved spacetime are written down using covariant formalism. We
discuss the stability of these string configurations by studying the solutions
of the linearized perturbed equations of motion.
