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8.1.2 MVS System Requirements
IMS/ESA requires a Type 2 SVC in the MVS nucleus and a Type 4 SVC in
LPALIB.
IMS/ESA Resource Clean-up Module and ABEND Dump Formatting Routine must
be link-edited into SYS1.LPALIB.
IMSESA.RESLIB must be APF authorized.
8.1.3 Data Base Descriptor (DBD)
1
Automatic field start calculation
Must code START= in the IMS/ESA DBD.
2
Automatic segment length calculation
Must code BYTES= in the IMS/ESA DBD.
3
FBA DASD Support
MVS does not support FBA (FIXed Block Architecture) DASD devices. This
requires changing the DEVICE= parameter of the DATASET statement to
the device type that will be used.
4
ACCESS Statement
The ACCESS statement is not supported in IMS/ESA. All parameters of the
ACCESS statement have equivalent function through parameters of the
DBD. This is provided in either DL/I or IMS/ESA DBDs. Therefore, the DBD
should be used for portability between DL/I IMS/ESA. The three types of
ACCESS statements and the required changes are:
HDAM DB
Access Stmt. DBD equivalent (DL/I or IMS/ESA)
RMRTM= RMNAME= (module,
CIANPT # of root anchor points,
PRIMCI= # of CIs in root addressable area,
RILIM record insert limit in bytes)
SEGM= data base root implied
SEQFLD= SEQFIELD of root implied if PARENT=0 is coded
SEQVAL= third subfield of the NAME parameter in the FIELD
statement defining the sequence field
Primary Index of HIDAM DB
Access Stmt. DBD equivalent (DL/I or IMS/ESA)
REF= separate DBD with ACCESS=INDEX needed
SEGM= NAME= of LCHILD in index DBD
SEQFLD= INDEX= of LCHILD in index DBD
In addition an LCHILD must be coded in the data DBD referencing an
index DBD.
Secondary Index for HD DB
Access Stmt. DBD equivalent (DL/I or IMS/ESA)
REF= separate DBD with ACCESS=INDEX needed
SEGM=target seg determined by which SEGM the LCHILD and XDFLD
follow in data DBD
SEQSEG=source seg
SEGMENT= of XDFLD
170 VSE to OS/390 Migration Workbook