GDGORDER
keyword specifies the order in which the individual generation data sets (GDSs)
will be concatenated.
The
values of Parameter are USECATLG, LIFO and FIFO.
USECATLG
- The GDS concatenation is ordered as specified in the GDG data set catalog entry.
When the GDGORDER keyword is not specified, the concatenation order from the
catalog definition of the GDG data set is used. However, the default
setting in the catalog entry for a GDG base data set definition is LIFO, to
match the setting for releases prior to z/OS V2.1.
LIFO
- The GDS concatenation is ordered with the newest GDS defined first and the
oldest GDS last.
FIFO
- The GDS concatenation is ordered with the oldest GDS defined first and the
newest GDS last.
Let
us explore this with an example. Suppose USERID.GDG has three generations as
shown below.
BROWSE USERID.GDG.G0001V00 Line
0000000000 Col 001 080
Command
===> Scroll
===> CSR
*********************************
Top of Data **********************************
GDG1
********************************
Bottom of Data ********************************
BROWSE USERID.GDG.G0002V00 Line
0000000000 Col 001 080
Command
===> Scroll
===> CSR
*********************************
Top of Data **********************************
GDG2
********************************
Bottom of Data ********************************
BROWSE USERID.GDG.G0003V00 Line
0000000000 Col 001 080
Command
===> Scroll
===> CSR
*********************************
Top of Data **********************************
GDG3
********************************
Bottom of Data ********************************
Case
1: When the GDGORDER keyword is not specified
The
below step copies all the generations of GDG to SORTOUT.
//STEP1 EXEC
PGM=SORT
//SORTIN DD
DISP=SHR,DSN=USERID.GDG
//SORTOUT DD
SYSOUT=*
//SYSOUT DD
SYSOUT=*
//SYSIN DD
*
OPTION
COPY
//*
Below
is the output of the above step. The effect is LIFO
BROWSE
-
SORTOUT STEP1 -
Page 1 Line 1 Cols
1-80
COMMAND
===> SCROLL
===> CURSOR
********************************
Top of Data ***********************************
GDG3
GDG2
GDG1
*******************************
Bottom of Data ********************************
Case
2: When GDGORDER=FIFO
The
below step copies all the generations of GDG to SORTOUT.
//STEP2 EXEC
PGM=SORT
//SORTIN DD
DISP=SHR,DSN=USERID.GDG,GDGORDER=FIFO
//SORTOUT DD
SYSOUT=*
//SYSOUT DD
SYSOUT=*
//SYSIN DD
*
OPTION
COPY
//*
Below
is the output of the above step.
BROWSE
-
SORTOUT STEP2 -
Page 1 Line 1 Cols
1-80
COMMAND
===> SCROLL
===> CURSOR
********************************
Top of Data ***********************************
GDG1
GDG2
GDG3
******************************* Bottom of Data ********************************
