The paper deals with the numerical asymptotical mean-square stability of
split-step ? methods for stochastic pantograph differential equations, which
is the generalization of deterministic pantograph equations. Instead of the
quasi-geometric mesh, a fully-geometric mesh, widely used for deterministic
problems, is employed. A useful technique, the limiting equation, for
deterministic problems is also extended to stochastic problems based on
Kronecker product. Under the exact stability condition, the stability region
of the split-step ? methods is discussed, which is an improvement of some
existing results. Moreover, such technique is also available to stochastic
pantograph differential equations with Poisson jumps. Meanwhile, compared
with the destabilization of Wiener process, the stabilization of Poisson
jumps is replicated by numerical processes. Finally, numerical examples are
given to illustrate that our numerical stability condition is nearly
necessary for stochastic problems.