This error can occur when ISPFILE is in use and when using the INSTALL clist delivered with CA Common Services r12 to invoke the simplified installation method. ISPFILE is used for File Tailoring and only one file can be allocated to ISPFILE at any given time.
Check if ISPFILE is in use.
- verify that your are getting into the simplified installation dialogs - from ISPF TSO command line
===> ex 'yourHLQ.ccsr12.INSTALL(INSTALL)'
- ISPF split screen and recreate the IKJ56246I message. Then issue the TSO LISTALC STATUS command to see what files are currently allocated to your session.
- If ISPFILE is in use, free ISPFILE and attempt the install again.