  In this paper, we give a complex analysis realization of
$\frak{gl}_n$-crystals and their tensor products. Motivated by this, we propose
that the WKB approximation of the Stokes matrices, of certain meromorphic
linear systems of ordinary differential equations, is characterized by
$\frak{gl}_n$-crystal structures on the eigenbasis of shift of argument
subalgebras of the universal enveloping algebra $U({\frak {gl}}_n)$.
