When entering SYSVIEW command XTSO under ISPF it's possible to get messages:
IRX0406E REXX exec load file SYSEXEC does not contain exec member GSVXXTSO.
REXX007E GSVXXTSO failed, rc 20
z/OS, TSO, ISPF
This has to do with the SYSVIEW CNM4BREX REXX data set. This data set must be available in the SYSEXEC DD concatentation. If the sysview.CNM4BREX data set is not preallocated in the user's TSO logon proc, then SYSVIEW will attempt to dynamically add it to the SYSEXEC DD during session initialization of the ISPF or TSO interfaces. If a REXX exec that resides in the SYSEXEC DD is being used to invoke SYSVIEW, the attempt to concatenate CNM4BREX to the SYSEXEC DD will fail because SYSEXEC is open.
A possible resolution is to add the SYSVIEW CNM4BREX data set to the SYSEXEC DD in the TSO logon procedure.
Another option is to invoke SYSVIEW via CLIST, as SYSEXEC would not be open and the dynamic concatenation will succeed.
A third option is to move the REXX exec being used to invoke SYSVIEW from a data set in the SYSEXEC DD concatenation to the SYSPROC DD concatenation.