System values cannot be created or deleted because they are not objects. For the same reason, they cannot be secured either. Only three operations are allowed on system values: listing, displaying, and changing.
Each system value has a name. In most cases, the name is made up using a method similar to that of naming commands: by putting together several abbreviations. This method makes system value names easy to remember. All system value names begin with the letter "Q."
The Work with System Values (WRKSYSVAL) command lists system values either on the display or on the printer.
If you select the printer, you get a report with the system values listed alphabetically by name along with their description, current value, and the value they had originally when the system was shipped to you. The report also marks the system values that no longer have the original value.
Whether you select a displayed or printed listing, you can select all system values, a certain group of them, or a single one. All you need to do is provide a different value to the SYSVAL parameter. For example, you can print a list that includes all system values as follows:
WRKSYSVAL SYSVAL(*ALL) OUTPUT(*PRINT)
You can also display a list of all security-related system values:
WRKSYSVAL SYSVAL(*SEC) OUTPUT(*)
You should obtain a printed list of all system values immediatelyafter you change any of them, even slightly. You should keep this listing in a safe place. Then, you can restore your system values if they become corrupted. System values can become corrupted, in the sense that they may change unexpectedly when you upgrade to a new release of the operating system.
Use the Display System Value (DSPSYSVAL) command to display individual system values. You must know the name of the system value. For example, you can check the system date by displaying system value QDATE:
If you don't know the name of the system value, you can use WRKSYSVAL to list them on the screen. Then, use the Roll keys until you find the system value you need. At that point, you can key in option 5 and press Enter.
If you use the DSPSYSVAL command, you also can direct the output to the printer by specifying OUTPUT(*PRINT), as follows:
DSPSYSVAL SYSVAL(QDATE) OUTPUT(*PRINT)
Remember that if you want to print all system values, or those that belong in a particular group, you can use WRKSYSVAL.
Use the Change System Value (CHGSYSVAL) command to change an individual system value. You must know the name of the system value and the type of value it expects. Most system values contain character data.
Changing a system value can change the way the system operates. Some changes to system values take effect immediately, others become effective the next time a user signs on, and others do not become effective until you IPL the system.
A much easier way to change system values is by using the WRKSYSVAL command, finding the proper system value, and keying in option 2. The panel informs you about the values and their meanings. If you use the CHGSYSVAL command, the command prompter gives you a generic input field and no information about the system value you are about to change.