Modifying the server configuration member for IMS Direct

Enable the IMS Direct parameters in the server configuration member.

About this task

This IMS Direct feature provides map reduce and parallelism support for accessing native IMS files. This support bypasses the requirement of having to use native IMS API calls by reading the IMS database files directly, similar to how an unload utility may work. This provides a significant increase in performance and reduced elapsed time in processing analytical type queries.

When an IMS SQL query is run, the SQL engine for the server will determine if the request is best to be run using IMS Direct (native file support) or if IMS APIs are required. The determination is based on database and file types supported as well as the size of the database. Virtual tables of the IMS segments are required just as before.

The following types of IMS databases are currently supported:

HIDAM/VSAM
HDAM/VSAM
PHDAM/VSAM
PHIDAM/VSAM

Compressed IMS databases are not currently supported by this enhancement.

The server configuration member is shipped in data set member hlq.SAZKEXEC(AZKSIN00) and copied to hlq.AZKS.SAZKEXEC(AZKSIN00) by the job in the AZKGNMP1 member for you to make your local modifications.

Procedure

In the AZKSIN00 member, locate the comment “Enable IMS Direct Map Reduce.”

Enable the IMS Direct parameters by changing if DontDoThis to if DoThis. Set the parameter IMSDIRECTENABLED to YES.

if DoThis then
  do
  "MODIFY PARM NAME(IMSDIRECTENABLED)    VALUE(YES)"
  "MODIFY PARM NAME(IMSDIRECTBUFFERSIZE) VALUE(1024)"
  "MODIFY PARM NAME(ACIINTSEGMP256)      VALUE(200)"
  "MODIFY PARM NAME(TRACEIMSDBREFRESH)   VALUE(YES)"
  "MODIFY PARM NAME(TRACEIMSDIRSTATS)    VALUE(YES)"

  "DEFINE IMSDBINFO", 
         "IMSID(xxxx)",
         "MODBLKS(your.MODBLKS)",
         "ACBLIB(your.ACBLIB)",
         "DFSRESLB(your.SDFSRESL)",
         "IMSDA(your.dynamic.allocation.lib)",
         "RECON1(your.RECON1)",
         "RECON2(your.RECON2)",
         "RECON3(your.RECON3)"                                         
end

The following table lists the parameters for configuring support for IMS Direct data stores:

Parameter	Description	Valid values
ACIINTSEGMP256	Required since IMS Direct uses the 256K ACI pool.	Numeric value. Default is 200.
IMSDIRECTBUFFERSIZE	Specified in KB, and should be greater than the size of the largest complete IMS database record (root + all dependent segments).	Numeric value.
IMSDIRECTENABLED	Enable IMS Direct support.	YES NO (default value)
TRACEIMSDBREFRESH	Generate trace message when IMS Direct map reduce discovery processing is performed.	YES NO (default value)
TRACEIMSDIRSTATS	Produce runtime statistics at the end of IMS Direct processing of a data set.	YES NO (default value)

The following table lists the parameters used to define the IMS data set names:

Parameter	Description	Valid values
ACBLIB	ACBLIB data sets contain the application control blocks (ACBs), which describe IMS applications, and data management blocks (DMBs), which describe databases and the applications that can access them.	your.ACBLIB
DFSRESLB	Load library that contains the major IMS modules.	your.SDFSRESL
IMSID	The IMS subsystem identification.	Up to 4 character ID.
IMSDA	Dynamic Allocation Library for IMSDBs and RECONs.	your.dynamic.allocation.lib
MODBLKS	Used to support dynamic resource definition. Contains the APPLCTN, DATABASE, RTCODE, and TRANSACT macros.	your.MODBLKS
RECON1	Primary RECONciliation dataset, which holds all of the resource information and event tracking information that is used by IMS.	your.RECON1
RECON2	An active copy of RECON1.	your.RECON2
RECON3	Spare RECON to be used when RECON1 or RECON2 are not useable.	your.RECON3