GCSSS1 Guarded Control Stack Switch Stack 1 Guarded Control Stack Switch Stack 1 validates that the stack being switched to contains a Valid cap entry, stores an In-progress cap entry to the stack that is being switched to, and sets the current Guarded control stack pointer to the stack that is being switched to. SYS 1 1 0 1 0 1 0 1 0 0 0 0 1 0 1 1 0 1 1 1 0 1 1 1 0 1 0 GCSSS1 <Xt> SYS #3, C7, C7, #2, <Xt> Unconditionally <Xt> Is the 64-bit name of the general-purpose source register, encoded in the "Rt" field.