The SYSHELP DD statement in the "standard" TSO logon procedure is missing the standard SYS1.HELP data set. I discovered this when I attempted to use the HELP command for a command that should be in SYS1.HELP. It was only recently that I investigated this matter in detail. A minor detail is the BLKSIZE for SYS1.HELP is smaller than the BLKSIZE for ISP.SISPEXEC.
Perhaps someone can correct this issue.