54 IMS Version 8 Implementation Guide
Assuming that database CUSTDB1 has 3 DBDS defined for (as pictured in Example 4-3),
consider the following GENJCL input:
GENJCL.IC DBD(CUSTDB1) COPIES(2) SMSNOCIC(4,S,C) ONEJOB DBREL(L)
This invokes the Image Copy 2 tool with the control statements in one execution step as
shown in Example 4-4.
Example 4-4 IC2 control cards
|...+....1....+....2....+....3....+....4....+....5....+....6...
//SYSIN DD *
2 CUSTDB1 DDNAME1A ICOUT11 ICOUT12 XLC4
S CUSTDB1 DDNAME1B
S CUSTDB1 DDNAME1C
The necessary skeletal JCL changes introduce the new keywords:
%SMSGRPA numeric value which controls group processing
%SMS1DSA numeric value indicating whether SAMEDS was specified
%GROUPA character value containing the group name or null
If you leave column one and column 61 blank, you are invoking the Image Copy 2 utility
without any use of the new features. However, you can use the existing skeletal JCL as
provided for exploiting as well as omitting the enhancements.
4.2 Parallel database processing
The parallel database processing enhancement is provided for improving the performance of
IMS after restart to reach a steady state faster. Multiple TCBs (using multiple threads) are
used for database authorization, dynamic allocation, open, close and end-of-volume
processes, which were running as serialized processes before. The parallel database
processing provides the following benefits:
򐂰 Exploits available processor power
򐂰 Reduces the elapsed processing times
򐂰 Achieves faster steady state response times
The parallel database processing is implemented by automatically exploiting additional
multiple task control blocks (TCBs). The parallel database processing is supported for full
function databases only. 10 TCBs are used in parallel. IMS uses an algorithm to divide the
DBREL( L | P ) if SMSNOCIC is
specified
L or P in column 59 for logical or physical processing
(*) smsopts in any order, following
the SMSCIC(smsopts) or
SMSNOCIC(smsopts) parameter
SAMEDS, COMPRESS, OPTIMIZE
SAMEDS S in column 1, multiple Image Copies into same single
output data set
COMPRESS C in column 60 for compression mode
n [1,2,3,4] n in column 61, applies the value for the OPTimize(n) option
Note: IMS Database Image Copy 2 enhancements require concurrent-copy capable DASD
controllers.

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