C CICS BAC CICS BAC ISPF administration interface
C,'CMD(CBKRCUST) NOCHECK NEWAPPL(CBKA)'
Also ensure that the data set containing the REXX EXEC CBKRCUST is added to your TSO logon PROC SYSPROC concatenation. The REXX EXEC is the only CICS BAC data set you need to add to the logon PROC, because CICS BAC dynamically allocates all the other required data sets during the ISPF administration interface startup.