I'm not a Z/OS expert (hardly even a novice), but the initial error says that that there was a read error on the PDF. Since it wasn't an "open" error, I presume that means that it did find and open the file, but is unable to actually read from it. This could be a problem with the job's definition of the file.
Check how this PDF was uploaded to zOS. Perhaps you didn't specify file was binary when it was uploaded?
The other thing to check, I think the INI option to load PDF should read LOGLoadPDFFile and not as you show LOGLoadTifFile.
< BitmapLoader:PDF >
Func = LOGLoadTifFile
Check the uploaded PDF file as well. Make sure the file was uploaded as binary. If you view the PDF on the mainframe and you see %PDF- at the beginning of the file, then it was uploaded incorrectly as ASCII. If you view the PDF and turn on the hex character display, the file should begin with hex characters 25 50 44 46 2D. If the file begins with those hex characters, check the end of the PDF file to see if it ends with the hex characters 25 25 45 4F 46 0D 0A.