17.00 - How the Attachment Facility Allocates Storage above 16 Megabytes - IBM CICS Interface for Teradata

IBM CICS Interface for Teradata® Reference

prodname
IBM CICS Interface for Teradata
vrm_release
17.00
created_date
June 2020
category
Programming Reference
featnum
B035-2448-220K

Under CICS/ESA 3.2 or above, the Teradata CICS Attachment Facility locates control blocks and buffers as explained in the following table.

CLI determines where to place the request and response buffers depending on the AMODE for the application and the software level of the TDP it is accessing.

CLI determines the response buffer location at the time of request initiation for the following functions based on the AMODE of the application and the setting of the Locate-Mode-Fetch option:
  • Connect
  • Runstartup
  • Initiate Request
  • Initiate With Protocol
WHEN the resource is . . . THEN it is located . . .
a CLIv2 control block (most, but possibly not all) above the line.
most CLIv2 buffers (as many as possible)
a session-related control block
an application request buffer and the application response buffer is eligible and the TDP version is 5.0 or greater
an AMODE31 application response buffer
an AMODE24 application response buffer and the Locate-Mode-Fetch option = N
a CLIv1 control block below the line.
a CLIv1 buffer
an AMODE24 application response buffer and the Locate-Mode-Fetch option is not N
an application request buffer and the TDP version is earlier than 5.0
a Preprocessor2 application response buffer

Usage Notes

CICS applications accessing the database should be linked AMODE 31 to enable both the request and response buffers to be placed above 16 megabytes.

If an application uses Locate-Mode-Fetch and is AMODE 31 at the time of request initiation, it must also execute in AMODE 31 when it references the results from a call to the CLIv2 Fetch function, since the returned address will be above 16 megabytes.

Several database-supplied transactions are located above the 16-megabyte line to further reduce the virtual storage requirements below 16 megabytes. These transactions will execute above 16 megabytes in all supported CICS releases, CICS/OS/VS and above.