This field specifies the LOAD parameter. The format of the LOAD parameter is:
- The first four characters (characters 1 through 4 of the LOAD parameter) specify the hexadecimal device number for the device that contains the I/O definition file (IODF) VSAM data set. This is also the device on which the search for the LOADxx member of SYSn.IPLPARM or SYS1.PARMLIB begins. The device number can be in the range X'0000' to X'FFFF'. If the number is less than 4 digits, specify leading zeros before the device number. This device must be in the same subchannel set as the IPL device. If you do not specify the device number, the system uses the device number of the system residence (SYSRES) volume.
- The next two characters (characters 5 and 6 of the LOAD parameter)
specify the suffix of the LOADxx parmlib member that the system is
to use. The LOADxx member contains information about the name of
the IODF data set, which master catalog to use, and which IEASYSxx
members of SYS1.PARMLIB to use.
The default for the LOADxx suffix is zeros. The system reads the LOADxx and NUCLSTxx members from SYSn.IPLPARM or SYS1.PARMLIB on the volume specified on the LOAD parameter (or the SYSRES volume, if a volume is not specified). Once the system opens the master catalog, the system reads all other members from the SYS1.PARMLIB data set that is pointed to by the master catalog. This SYS1.PARMLIB might be different from the SYS1.PARMLIB data set to which the LOAD parameter points.
For more information about LOADxx, see the description of LOADxx in z/OS MVS Initialization and Tuning Reference.
- The next character (character 7 of the LOAD parameter) specifies
the prompting and message suppression characteristics that the system
is to use at IPL. This character is commonly known as an initialization
message suppression indicator (IMSI).
Suppressing Informational Messages: Some IMSI characters suppress informational messages from the system console, which can speed up the initialization process and reduce message traffic to the console. It can also cause you to miss some critical messages, so you should always review the hardcopy log after initialization is complete.
When the system suppresses informational messages, it displays the following messages:- Messages with descriptor codes 1, 2, 3, 11, or 12
- Write-to-operator with reply (WTOR) messages
- Command responses
- Synchronous messages that can indicate problems during initialization.
It does not display the contents of a parmlib member, even if the L option has been specified.
Prompting for Operator Responses: You can specify an IMSI character that tells the system to issue a MASTER CATALOG prompt, a SYSTEM PARAMETERS prompt, both, or none:- If the system issues a MASTER CATALOG prompt, the operator response overrides the values that are specified on the SYSCAT parameter in the LOADxx parmlib member.
- If the system issues a SYSTEM PARAMETERS prompt, the operator response overrides the values that are specified on the SYSPARM parameter in LOADxx. Also, if LOADxx specifies the IEASYMxx parameter which in turn specifies a SYSPARM parameter for IEASYSxx, then the operator response also overrides the values that the SYSPARM parameter in IEASYMxx specifies.
- If the system does not prompt the operator, the system uses the values specified in LOADxx. If the SYSCAT and SYSPARM statements are not specified in LOADxx, the system issues one or both prompts to obtain the missing information.
Prompting for the Name of the Master Catalog: If you choose an IMSI character that tells the system not to prompt for the master catalog name, the system uses the name specified on the SYSCAT parameter in the LOADxx parmlib member.
The default for the system parameter prompt is to use IEASYS00 in SYS1.PARMLIB, and the default for the master catalog prompt is to use SYSCATLG in SYS1.NUCLEUS.
The following table shows the possible values for the IMSI character. The default value is period (.).Table 1. Possible Values IMSI Characters IMSI Character Display Informational Messages Prompt for Master Catalog Response Prompt for System Parameters Response period (.) or blank No No No A Yes Yes Yes C No Yes No D Yes Yes No M Yes No No P No Yes Yes S No No Yes T Yes No Yes - The last character (character 8 of the LOAD parameter) specifies the alternate nucleus identifier (0-9). Use this character at the system programmer's direction. If you do not specify an alternate nucleus identifier, the system loads the standard (or primary) nucleus (IEANUC01) and an architectural extension of the nucleus (IEANUC11 or IEANUC21), unless the NUCLEUS statement is specified in the LOADxx member. For more information, see z/OS MVS Initialization and Tuning Reference.
- Decide whether to accept the system prompt indicator default.
The default causes the system to suppress messages and not prompt
the operator. You might miss critical messages during initialization,
so you should review the hardcopy log.
New installations might want to select prompt feature A (display all messages and prompt the operator) or M (display all messages but do not prompt operator) on the Hardware Management Console while validating changes and analyzing system errors during the initialization process. Specifying either A or M might increase message traffic.
- Omit the LOAD parameter when you accept all the IBM-supplied defaults.
- Each character in the LOAD parameter is positional. If you change any of the defaults you must retype the characters or use periods (....) to hold the positions.
- You cannot leave any leading spaces blank, unless the defaults are accepted for the rest of the LOAD parameter.