Normally, the communication part of the VTAM® application program issues the OPEN macroinstruction. The OPEN macroinstruction cannot be issued from an exit routine.

When using persistent LU-LU session support, the recovering application program can issue the OPEN ACB from the same or a different address space. With MNPS, the ACB can be OPENed on another VM within the sysplex.

See Operating system facilities, for additional information pertaining to ACBs.