Changing System Symbols

When you update symbols, the entire system symbol table is re-built, and the old system symbol table remains in storage; this storage is never freed, for system integrity reasons. As a result, you can avoid wasting common storage if you do a group of updates together instead of doing individual updates. The system symbol table is in subpool 245 (ESQA) and may be as large as 32512 bytes. The size depends upon the number of symbols that you have defined. In general, the number of bytes in the table can be calculated as the sum of:

• 4
• Number_Of_Symbols multiplied by 16
• Length of every symbol name (including the leading ampersand and trailing period)
• Length of the value for every symbol

The size of the current system symbol table can be viewed by the DISPLAY SYMBOLS,SUMMARY command. An example of the command output is:

SY1  IEA994I STATIC SYSTEM SYMBOL INFO   
SYMBOLS DEFINED: 12                      
CURRENT TABLE SIZE: 344 BYTES            
MAX TABLE SIZE: 32512 BYTES  

To execute the IEASYMU2 program, you would run the following JCL (noting that IEASYMU2 will be in the LNKLST so no joblib or steplib should be used):

//IEASYMU2 JOB ...
//IEASYMU2 EXEC PGM=IEASYMU2,PARM='...'

The input parameter is specified using the PARM keyword on the EXEC card, in the format:

PARM=′SYMNAME1=VALUE1 SYMNAME2=VALUE2 ...SYMNAMEN=VALUEN′

where:

• All updates by IEASYMU2 are controlled by RACF facility class entity IEASYMUP.symbolname (without the leading ampersand and trailing period). If the security product does not grant UPDATE access to the requestor for every symbol requested by the job, the job does not complete successfully and the symbol table is not updated.
• The name of each "SymnameN" should not contain the leading "&" or the trailing ".".
• The first symname=value specification must begin at the first character of the parameter. Each symname=value specification must be separated from the preceding one by exactly one blank.
• There must be no trailing blanks at the end of the parm string.
• The value must not have blanks.
• No translation to uppercase is done by the processing, so be careful to put everything in uppercase as needed.
• You can change the values of symbols (including the length).
• You can add new symbols.
• You cannot have an "&" as part of the symbol name
• You can use symbolics in defining the value if you invoke this as a started task or started job. In this case, the symbols are resolved by the system before IEASYMU2 runs.
• When there are symbolics used in defining the value that are not resolved by the system before IEASYMU2 runs (perhaps because you ran this as a batch job):
  • They must be resolvable by the system symbol table that existed before this running of IEASYMU2.
  • The input parameter area may be modified by the IEASYMU2 processing.
• The specified symbol name must be no longer than 8 characters (as it does not contain the leading "&" or the trailing ".").
• You may not specify the system-defined symbols SYSPLEX, SYSNAME, SYSCLONE, SYSR1, SYSALVL, SYSOSLVL.
• The specified value must be no longer than the specified symbol name plus one.
• Less syntax checking of operands may be done for the IEASYMU2 program than is done for the SETLOAD xx,IEASYM command.
• If the parameter string exceeds 100 bytes (or even if it does not), you can use the PARMDD (also known as LONGPARM) support of z/OS V2R1 to specify the parameters within the DD identified by using PARMDD=ddname on the EXEC PGM= statement of the JCL. Care must be taken if using PARMDD, due to the PARMDD rule of stripping off all trailing blanks on a given line. Thus:
  • The first symname=value pair must start in column 1 of the first line
  • You should not split a symname=value pair across lines (primarily for clarity)
  • When continuing onto a second or subsequent line, begin that line with the symname=value pairs starting in column 2
  • For example, (the first line of the example is not part of your input; it is just used for showing the starting column)

    1--------------------------------
    SYMNAME1=VALUE1 SYMNAME2=VALUE2
     SYMNAME3=VALUE3
     SYMNAME4=VALUE4 SYMNAME5=VALUE5

• You may not provide more than 255 input symbols
• The resulting system symbol table must not exceed 32512 bytes.
• Output messages are written by WTO with routing code 11 and MCSFlag indicating hardcopy-only.
• As with the SETLOAD xx,IEASYM command, a change to the system symbol table results in sending ENF signal 73 and also re-running CHECK(IBMSUP,SUP_SYMBOL_TABLE_SIZE).
• Messages IEASYMU01I, IEASYMU02I, IEASYMU03I, and IEASYMU04I might be issued.