Digging into the TCAM TSO problem running RPF correctly

 CLUES TO PURSUE

Some times that RPF would want to clear the screen, it does not happen. The impact of this is screen residue including attribute bytes protecting fields that should no longer exist. On the other hand, when the cursor gets to the bottom of the screen in line mode, it clears just fine to present the next 'screenful'. 

The terminal is only in line mode. That is, when you hit enter the cursor is moved down a line and periodically when the bottom of the screen is reached, three asterisks are shown to cue the user that lines weren't written because the screen is 'full'. PF24 is supposed to toggle TCAM between line and full screen modes, but it does nothing. The terminal only operates in line mode.

EXPERIMENTATION TO UNDERSTAND THE ISSUE

The only software that appears to malfunction is RPF. RPE, another full screen tool, works fine. All the line oriented applications and commands work well. I began looking through the source code of RPF and making small changes to see if I could localize the problem. 

RPF worked partially. Some menus were displayed, others were not.

• The initial splash screen at startup is not displayed
• The main menu is not displayed. This offers 11 choices, 0-9 and X
• Choice 0 will display its own menu, as do choices 3, 7, 8, and 9. X ends RPF
• Choices 1, 2, 4, 5, and 6 do not display their menus
• Within choice 0's submenu, there are 5 choices plus exit. Only two display menus

I first looked at the streams being written and the code in the module producing it, to see if there was an obvious common element or code being executed. Nothing obvious as far as I could tell. I then moved the screen write (TPUT write to TCAM) earlier in the modules to see if bypassing some code would clear the problem. Nothing changed in this case either.

I then slightly modified the TPUT call. There are three types of TPUT - ASIS, FULLSCR and NOEDIT - and RPF was almost exclusively using NOEDIT. I changed the startup code to ASIS and the splash screen appeared! 

This had a deleterious effect on operation under VTAM, as it converted the splash screen into a line oriented rather than full screen write, so I had the three asterisks that mark a continuation at the bottom of a screen. It did not behave that way under TCAM. 

I went into the code that produced the main menu to change the TPUT statements to ASIS. This did put up the menu but oddly, in sections with the line continuation characters between each group. ASIS supposedly passes the message directly through TCAM to the terminal, while FULLSCR and NOEDIT make some dynamic translations including decisions about line mode versus full screen. 

About this time, I came across the release notes of newer versions of RPF which mentioned changes dealing with the NOEDIT version of TPUT and correcting behavior under TCAM. That seemed to match my symptoms thus I proceeded to download and install the latest release V1R8M3 to see what it did. 

Alas, while it improved the behavior of some screens it still didn't show the splash screen, main menu or several of the choices from the main menu. Where it did display the menus in the past, residual characters were left on the screen from prior writes. With this new release, those menus that did display correctly erased the screen first so at least we had progress.

COMPARING TK4- AND MOSELEY 3.8J VERSIONS FOR RPF EXECUTION

RPF is said to work properly under TCAM in the TK4- version of MVS 3.8J while it obviously does not work in the version of 3.8J I just built from the Jay Moseley site. I had Tk4- installed and will first verify that it works well, then start examining the two systems to look for differences that might explain this divergence.

In particular, I will look for:

1. Differences in parameters in library members and procedures related to RPF, TSO, TCAM
2. Different APARS and local modifications applied to the two versions of MVS
3. Any modifications applied to RPF