Using CICS Transaction Gateway for z/OS connecting via an RCI link, the security setting is ATTACHSEC+VERIFY.
But you may get this error message:
(request failed with ECI_ERR_SECURITY_ERROR ( rc-27))
It means that there is an issue with the SURROGAT Class.
To resolve this, you can either specify:
...in the DFHXCOPT Options Table, or run the following commands:
TSS ADD(AcidOwner) SURROGAT(*.DFHEXCI)
TSS PER(ALL) SURROGAT(*.DFHEXCI) ACCESS(READ)