CA IMS Database Tools r20.
The reason for the missing archive SAMPJCL file was caused by the customer running an uncompress' and 'pax -rvf' on the S0001.MF20.MSPS.IMS.R200BP0.IMTK0B0.SAMPJCL.pax.Z. file prior to the execution of the UNZIPJCL job. This process caused the file to be renamed to S0001.MF20.MSPS.IMS.R200BP0.IMTK0B0.SAMPJCL.pax (without the 'Z'), thus preventing the UNZIPJCL's job to find the fully qualified SAMPJCL file name (ending with the 'Z').
The customer corrected this condition by deleting the IMTK0B0 directory and contents and then starting over with the unpaxing of the IMS r20 DVD image, and subsequent editing and invocation of the UNZIPJCL member found in the /IMTK0B0 directory.