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VPE Control DD statements control the operation of VPE by their presence within a jobstep. With one exception, these special DD statements do not specify data sets. Rather, special DUMMY DD statements in the jobstep and artificial data set names invoke VPE and control its operation. VPE does not open the artificial data set names you specify on these DD statements. However, be careful in coding the VPE Control DD statements which include the artificial data set names because the data sets are allocated and deleted by job control. These DD statements must be completely valid to job control even though they are not opened and used to create a data set. You need to code them like the following:
//ddname DD DSN=ddname1.ddname2.ddname3...ddnamen, // UNIT=DISK,SPACE=(TRK,0)
The special VPE ddname
The 1st application ddname you are referencing
The 2nd application ddname you are referencing
The nth application ddname you are referencing
Unlike the VPE Rules Table, Control DD statements can be coded by anyone who wants VPE operation, without refreshing the VPE Operating System interfaces, and without the involvement of the storage administrator. They are also much more easily and quickly processed by VPE, allowing early exit from the SVC intercept code.
In order for the Special Control DD statements to invoke and control VPE, the ALLOW=YES parameter must be specified (or be allowed to default) on the SYSOPT statement in the VPE Rules Table. Conversely, the Special Control DD statement functionality can be completely disabled by coding ALLOW=NO on the SYSOPT statement in the VPE Rules Table.
Note: The VPEIGNR Control DD Statement always disables VPE in that step even if ALLOW=NO is coded in the VPE Rules Table.
The VPEONALV DD statement activates VPE for all appropriate VSAM files in the jobstep. In most cases, VPE can correctly select those VSAM files to optimize completely automatically. You can see which files were selected and how they were optimized by VPE on the Run Statistics Report. The syntax of the VPEONALV DD statement is:
//VPEONALV DD DUMMY
The VPEBUF DD statement specifies the target buffer pool size for the jobstep. The default is 4 Mb. The size of the buffer pool requested is specified in Mb as the last two characters of the ddname. The syntax of the VPEBUFnn DD statement is:
//VPEBUFnn DD DUMMY
For example, VPEBUF99 sets the target buffer pool size to 99 Mb. A value this large eliminates most I/O.
The VPEIGNR DD statement deactivates VPE for the jobstep. This DD statement always functions and takes precedence, even if ALLOW=NO or PRECEDENCE=VPEDD is coded on the SYSOPT statement in the VPE Rules Table. The syntax of the VPEIGNR DD statement is:
//VPEIGNR DD DUMMY
The VPEONnn DD statement directs VPE to optimize the files referenced by the ddnames specified as nodes of the DSNAME portion of the DD statement. The nn portion of the DD statement is a number from 00 through "09", allowing up to 10 VPEONnn DD statements per jobstep. The syntax of the VPEONnn DD statement is:
//VPEONnn DD DSN=ddname1.ddname2.ddname3...ddnamen, // UNIT=DISK,SPACE=(TRK,0)
If your security system requires a specific value as the first qualifier of the data set name, VPE allows you to code any value there without requiring it to match a DD statement coded in the job. As usual for a real DD statement, the artificial data set name coded on this special DD statement must not exceed 44 characters in length. The following example activates VPE for the data sets specified by DD cards VSAM1 and VSAM2:
//VSAM1 DD DSN=MY.VSAM.FILE.ONE,DISP=SHR //VSAM2 DD DSN=MY.VSAM.FILE.TWO,DISP=SHR //VPEON00 DD DSN=VSAM1.VSAM2, // UNIT=DISK,SPACE=(TRK,0)
The VPEONG DD statement works the same as the VPEONnn DD statement except that the ddnames coded as nodes of the artificial data set name can be ddname prefixes or wild cards. The syntax of the VPEONGnn DD statements is:
//VPEONGnn DD DSN=ddname1.ddname2.ddname3...ddnamen, // UNIT=DISK,SPACE=(TRK,0)
The following example activates VPE for the data sets specified by DD cards VSAM1 and VSAM2 using the ddname prefix VSAM:
//VSAM1 DD DSN=MY.VSAM.FILE.ONE,DISP=SHR //VSAM2 DD DSN=MY.VSAM.FILE.TWO,DISP=SHR //VPEONG00 DD DSN=VSAM, // UNIT=DISK,SPACE=(TRK,0)
The VPELSRPB DD statement directs VPE to acquire LSR pool space below the 16 Mb line. This is necessary in applications which are not MVS/XA-ready and use LOCATE mode I/O. This DD statement always functions and takes precedence, even if ALLOW=NO or PRECEDENCE=RULES is specified. The syntax of the VPELSRPB DD statement is:
//VPELSRPB DD DUMMY
The VPEVSTS DD statement is a real SYSOUT DD statement which VPE uses to print error messages and statistics. If it is not included in the jobstep, then VPE dynamically allocates it. The syntax of the VPEVSTS DD statement is as follows, where n is a valid SYSOUT class for your JES system:
//VPEVSTS DD SYSOUT=n
The VPEVRPT DD statement directs VPE to produce the VSAM Recommendations Report. See VPE Reports in this chapter for information about the report. In addition, this statement generates warning messages that reflect conditions relating to the IDCAMS definition of clusters or their current status as observed in the catalog. The syntax of the VPEVRPT DD statement is:
//VPEVRPT DD DUMMY
The VPEWRKnn DD statement directs VPE to turn on Deferred Write and Sequential Insert Strategy performance enhancement techniques for the files referenced by the ddnames specified as nodes of the DSNAME portion of the DD statement. The nn portion of the DD statement is a number from 00 through 09, allowing up to 10 VPEWRKnn DD statements per jobstep. The syntax of the VPEWRKnn DD statement is:
//VPEWRKnn DD DSN=ddname1.ddname2.ddname3...ddnamen, // UNIT=DISK,SPACE=(TRK,0)
If your security system requires a specific value as the first qualifier of the data set name, VPE allows you to code any value there without it requiring to match with a DD statement coded in the job. As usual for a real DD statement, the artificial data set name coded on this special DD statement must not exceed 44 characters in length.
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