Including Fast Path in a DCCTL or DB/DC system definition

During a DCCTL or DB/DC system definition process, you can specify which Fast Path application programs and resources should be included in the IMS system.

Fast Path drives relatively simple transaction and database processing through the IMS system at high transaction rates. You must assess whether the combination of Fast Path regions and other regions, as well as the increased requirement for control program storage, can be supported in your system definition.

To include the Fast Path control program facilities and to reserve certain resources for Fast Path in an IMS online system, specify FP=Y in the DFSPBxxx member in the IMS PROCLIB data set. To include Fast Path processing and transactions in a DCCTL system, specify FP=Y in the DFSPBxxx member in the IMS PROCLIB data set.

If you specify FP=N, and you attempt to use a Fast Path resource or command, the results are unpredictable.

To specify Fast Path options and buffer sizes for an IMS online system, use the Fast Path parameters in the IMS procedure or the Fast Path section of the DFSDFxxx PROCLIB member.

You do not need to include the Fast Path parameters for a DCCTL system because Fast Path parameters apply only to Fast Path databases, and the DCCTL environment does not support Fast Path databases. Although the DCCTL environment does not support Fast Path databases, it does support Fast Path processing and transactions.

Use the following macros to describe the Fast Path application programs and associated resources:

APPLCTN: Declares the application programs
RTCODE: Directs input messages to Fast Path programs
TRANSACT: Declares the transaction code and processing characteristics

In an IMS DB/DC system, you can specify the following keyword parameters:

OTHR: Keyword specifying how many output threads are to be used for the asynchronous DEDB update processing.
The OTHR= parameter can have any value from 1 to 32,767. If a value is not specified, the default is 255. If 0 or a value greater than 32767 is specified, the default is 2. If a value from 1 to 32767 is specified, the specified value is used.
DBFX: Keyword specifying the number of buffers to be set aside for DEDB updates used by sync point processing. These buffers are part of the total number given for DBBF.
DBBF: Keyword specifying the maximum number of buffers available to the online system for MSDB and DEDB processing. The range for both numbers is 1 - 4␠294␠967␠295. The default values are 4 for MSDBs and 10 for DEDBs.
BSIZ: Keyword specifying the actual size of an individual buffer. The control interval size is 512 bytes, 1␠KB, 2␠KB, 4␠KB, or a multiple of 4␠KB (up to 28␠KB), depending on the size of the largest control interval (CI) used for DEDB processing.
FPBP64x: Specifies a number of Fast Path 64-bit buffer manager options. If you choose to use the Fast Path 64-bit buffer manager (FPBP64=Y), the DBBF, DBFX, and BSIZ parameters that define Fast Path buffers are ignored. For complete information about the FPBP64x parameters, see DFSDFxxx member of the IMS PROCLIB data set.