CICS BAC List VSAM files fails with CBKDC8008E Unknown Error EXCI Error codes: 00000010 00000261 010800B0

The Error codes in message CBKDC8008E for an EXCI request map to the EXCI return codes as follows:

In assembler copybook DFHXCRCD the first word is the response code:
EXCI_SYSTEM_ERROR EQU 16

The 2nd word is the reason code x'261' which maps to:
IRC_CONNECT_FAILURE EQU 609

CICS Transaction Server (CICS TS) module DFHXCPRH uses the IRC return code for the subreason fields:

     *  None of the above, just set connect system error and use
     *  IRPs return code as the subreason field
     *
           MVC   EXCI_RESPONSE,=A(EXCI_SYSTEM_ERROR) Set response
           MVC   EXCI_REASON,=A(IRC_CONNECT_FAILURE) Set reason

CICS TS module DFHIRPS just past label IRSECFRE following a RACROUTE AUTH call, saves the SAF RC as then 2nd byte:

       SLL   RE,16               Reposition SAF RC

...and the reasons in byte 1, 3 and 4:

       ICM   RE,B'1011',=AL3(256*256***IRERQAUT**+**IRERRSCF**)

IRC Interregion control blocks in the CICS TS documentation describes the qualifiers:

 HEX  00B0  IRERRSCF  Security check failed  
 
     Qualifiers for security check failure  

 HEX  01  IRERQAUT  IRERRSCF qualifier AUTH denied access

Checking z/OS syslog, I then found the message ICH408I for resource DFHAPPL where the userid did not have access.

See CICS BAC support for CICS EXCI security in the CICS BAC documentation which explains the EXCI security requirements for the TSO (ISPF) user.