Online User Requirements Tables › Planning the User Environment

Planning the User Environment

Determining Scope of URTs

Every CICS program requesting CA Datacom/DB service requires at least one URT defined in the CICS region. For a task to execute, the URT needed for each request must be open or eligible to be opened. During normal operation, all URTs may remain open. During recovery and reload, however, the processing on the databases being recovered or reloaded must be quiesced by closing the URTs which declared them open for access or update.

Note: For more information, see the CA Datacom/DB Database and System Administration Guide.

The contents of URTs can be based on the applications that use them, as in batch. However, for CICS they need not be, since CA Datacom CICS Services makes a URT selection for each request rather than for each application. For example, if a batch program reads data from three databases, the URT you link to that program must define the required tables from each of the three databases. If an online application reads the same three databases, you could define CA Datacom/DB tables for each of these databases in different URTs and CA Datacom CICS Services would select the appropriate one as needed.

Note: You may alter the DCCTFPR exit to control URT selection with a prefix.

Determining Number of URTs to Define

Generally, you define multiple URTs. The amount of time it takes to open and load a URT increases with the quantity of CA Datacom/DB tables within the URT and by the number of URTs to be loaded. This processing time can be included in CICS initialization by:

• Using the default PLT method to open a URT at STARTUP as described in the information regarding the AUTOn= parameter used with the DEFER= parameter of the DBCVTPR macro, or
• Defining the URT to be opened when required by using the AUTO= parameter as described in the information about controlling resources with operational commands in the User Guide.

Defining SQL URTs

CA Datacom CICS Services opens only one URT. If all your programs use SQL, define only one URT containing no CA Datacom/DB tables.

Procedure for Preparing URTs

Your responsibilities include the following:

1. Define the URTs required by your CICS applications as described in Coding the URT Macros.
2. Assemble and link each URT separately.

   Note: URT cannot be assembled/linked as RENT.

3. Link edit URTs into the CICS library, specifying the 8-byte module name as DBURTnnn if PREFIx=DBURT. For the URTs greater than 999 and PREFIX=DBURT, then the 8-byte name would be DBURnnnn. DBURT is the default value for the DBCVTPR PREFIX= parameter. You provide the name for a given URT in the JCL used for assembling and link editing. The name is a combination of the selected prefix name and a sequential number. For information about what happens with the prefix when a higher number than 999 is used, and to highlight that aspect of the following examples, see PREFIX= and Assembling and Linking Each URT.
4. Use the DFHCSDUP batch utility or the online CEDA transaction to define each new URT in the CICS CSD data set:

   DEFINE PROGRAM(DBURTnnn)GROUP(B114GRP)LANGUAGE(ASSEM)RESIDENT(YES)CEDF(NO)
   

   Or, in the case of a URT number greater than 999:

   DEFINE PROGRAM(DBURnnnn)GROUP(B114GRP)LANGUAGE(ASSEM)RESIDENT(YES)CEDF(NO)
   

5. Define the MAXURTS= value in DBCVTPR to accommodate the number of URTs you desire.

URT Selection

Before accessing CA Datacom/DB, CA Datacom CICS Services passes control to the URT selection module (DCCTFPR). This module determines which URT CA Datacom CICS Services uses when processing a request. Your company may write a prefix CA Datacom CICS Services URT Selection Exit for specific security, or accounting purposes.

Details on the standard URT selection logic are described in URT Selection (DCCTFPR). A simplified explanation of URT selection processing for a non-SQL request follows:

1. Examines the Request Area to determine the name of the CA Datacom/DB table to be accessed and the DBID in which the table resides.
2. Searches available URTs (URTs) in ascending order by number and selects the first one it encounters which is eligible for processing the request. The following criteria determines eligibility:
   • If the Request Area contains only a DBID, the first URT within the list having the same DBID is used.
   • If the Request Area contains both a table name and a DBID, eligibility is based on how SYNONYM= is coded in the URT. If SYNONYM=NO, the URT must list a matching table name. If SYNONYM=YES, the URT must list a matching table name and DBID.

     Note: If, within one URT, the same TBLNAM= is specified twice for different DBIDs and has SYNONYM=NO for the first in the list but SYNONYM=YES for the second in the list, CA Datacom/DB finds a match on the first entry and does not look for the second entry. If two URTs have the same TBLNAM= specified for different DBIDs and the lower numbered URT specifies SYNONYM=NO and the higher numbered URT specifies SYNONYM=YES, CA Datacom CICS Services selects the lower numbered URT without regard to DBID.