Partial implementation runs without resident memory and needs only one user exit. Deactivated implementation runs much like partial implementation, but requires a few lines of code in the applications it supports. It is useful for applications to be installed at multiple locations, some of which do not otherwise support OHF, or for forcing a help window onto a screen without the user's request. Environment Use OHF with CICS 1.7 or greater and any 3270-type terminal or 3270 emulator. Full operation of OHF requires one or more CICS user exits and 300 bytes of resident memory plus 9 bytes for each terminal in the region.
Limited operation is possible, however, without user exits and resident memory.
OHF does not use the Terminal Control Table User Area. OHF operates properly in MRO, but it must be installed in your Terminal Owning Region. For a standard 24 x 80 screen, that's 4,000 bytes. OHF runs below the 16 Mg line. To allow color and highlighting, the VTAM log-on mode table for a given CRT must support extended attributes, and it and the CICS TCT must be consistent with one another.