Defining the LRQ file to the CSD

There is a default FILE definition, DFHLRQ, for the local request queue data set in the CICS®-supplied RDO group DFHCBTS. DFHCBTS is included in the default CICS startup group list, DFHLIST. Figure 36 shows the default definition.

Figure 36. The supplied, default, FILE definition for the LRQ
DEFINE   FILE(DFHLRQ)   GROUP(DFHCBTS)
DESCRIPTION(Scheduler Services - Local Request Queue)
         RLSACCESS(NO)              LSRPOOLID(1)
         READINTEG(UNCOMMITTED)     DSNSHARING(ACCREQS)
         STRINGS(10)                STATUS(ENABLED)
         OPENTIME(FIRSTREF)         DISPOSITION(OLD)
         DATABUFFERS(11)            INDEXBUFFERS(10)
         TABLE(NO)                  RECORDFORMAT(V)
         ADD(YES)                   BROWSE(YES)
         DELETE(YES)                READ(YES)
         UPDATE(YES)                JOURNAL(NO)
         JNLREAD(NONE)              JNLSYNCREAD(NO)
         JNLUPDATE(NONE)            JNLADD(NONE)
         JNLSYNCWRITE(NONE)         RECOVERY(BACKOUTONLY)
         FWDRECOVLOG(NO)            BACKUPTYPE(STATIC)
 

For performance reasons, you may want to change the default definition. For example, because the LRQ is frequently accessed it may be sensible to put the file in its own LSR pool, or to define it to use VSAM nonshared resources. This way, BTS operations will not be affected by other file accesses.

If it’s possible that, in your BTS system, many activities may be initiated at the same time (consider a banking application that produces a statement for each customer at the same time each month), it may be a good idea to set the number of strings and buffers to the value of the MXT system initialization parameter. Doing so would avoid string and buffer waits. (You could also use TRANCLASS definitions to further throttle the number of concurrent transaction instances and thus LRQ file accesses.)

To alter the definition of DFHLRQ, you can do either of the following:

  1. Edit the supplied default FILE definition in the DFHCBTS group, and cold- or initial-start your CICS region. (The DFHCBTS group is supplied by IBM® but you are not prevented from modifying it.)

    If you use this method, you are recommended to take a backup copy of the definition after you have altered it, to prevent your changes being lost if maintenance is applied to the CSD.

  2. Create your own FILE definition for DFHLRQ in a CSD group other than DFHCBTS, and cold- or initial-start your CICS region. Your CSD group must be installed before the DFHCBTS group. (On startup, when CICS encounters the definition in the DFHCBTS group after your own definition has been installed, it issues message DFHAM4803 as a warning.)
Note:
To change the operational attributes of the DFHLRQ file by means of SPI commands while CICS is running, you must first close the file, which may affect BTS operation. Not all attributes can be changed by SPI commands.

Related concepts
Local request queue data set
What are CICS business transaction services?
Related tasks
Defining repository files to the CSD
CEDA DEFINE PROCESSTYPE
[[ Contents Previous Page | Next Page Index ]]