Exiting the Variable Zoom Screen

• To exit the Variable Zoom screen and save the changes, press END (PF03/PF15).
• To exit the Variable Zoom screen without implementing the changes, press RESET (PF04/PF16), or type CANCEL in the COMMAND line and press Enter.

Changes made to the Variable database through the online Variable Database facility are not available to Control-M or Control-O until the modified database is reloaded into memory by the appropriate operator command (F CTMCMEM,LOADGLOBAL=IOAVAR), as described in the INCONTROL for z/OS Administrator Guide.

However, changes made to the Variable database through DO SET and SET VAR statements in Control-M, and SET statements in the JCL, are kept in memory. The Variable database file is automatically updated during the next internal Control-M interval cycle (or when the Control-O or CMEM monitor is stopped.)

WARNING: Updating the IOAVAR physical database using screen IV in MODE ADMIN is hazardous in a live system!

The following discussion concentrates on the IOAVAR database which is used by Control-M, but similar problems might occur with Control-O only pools.

Updating the IOAVAR physical database using screen IV in MODE ADMIN in a live system can lead to

• variables getting lost
• blank variable names

The following scenario can lead to variables getting lost.

The IOAVAR database can be changed in the following ways:

• By Control-M SET operations (SET VAR in the Job Scheduling Definition, %%SET in the JCL) that change the live database in memory.

  These changes are saved in the physical database when the WRITEGLOBAL=IOAVAR command is automatically issued.

  Only a WRITEGLOBAL saves these changes to the database.

• By manually changing the physical database via screen IV in MODE ADMIN.

  These manual changes are brought to the live database in memory by a LOADGLOBAL command.

  A LOADGLOBAL=IOAVAR is performed automatically when Control-O/CMEM starts.

  A LOADGLOBAL=IOAVAR can be issued manually when changes that are made to the physical database must be brought into the live database in memory while the system is active.

  A LOADGLOBAL=IOAVAR replaces the entire existing copy of the database in memory.

It is hazardous to update the IOAVAR physical database using screen IV in MODE ADMIN in a live system and issue a LOADGLOBAL because in a live system an IOAVAR variable might be updated at any time and if the LOADGLOBAL is issued just before the WRITEGLOBAL is issued, it will cause recent changes that have not yet been saved with the WRITEGLOBAL to be wiped out.

The following scenario can lead to blank variable names:

When a variable is deleted from the database via IV screen in MODE ADMIN in a live system, and until a LOADGLOBAL=IOAVAR is issued, the variable remains in memory. If the deleted variable is added or updated by Control-M before the LOADGLOBAL=IOAVAR is issued, the variable will still be found in memory, and only the VALUE of the variable will be updated. The WRITEGLOBAL=IOAVAR writes only the value of changed or updated variables to the database (even if the value has not actually changed).

The end result will be that the physical database will include only the VALUE of the IOAVAR variable which has been deleted and updated but without its VARNAME which has been deleted. When viewed in IV screen in MODE ADMIN, blanks will appear in the VARNAME field.