GDGALLOC = GENERATION | DSNAME

This parameter specifies whether IBM® Connect:Direct® allocates GDG data set by generation or data set.

Note:

Do not specify both GDGALLOC=GENERATION and GDGENQ=NO. IBM Connect:Direct will change GDGENQ=NO to GDGENQ=YES.

Value Description
GENERATION IBM Connect:Direct allocates by generation, so the allocation is DATA.SET.NAME(xx), where (xx) is the relative generation such as (+1), (-3), (0), and so on. Use for SMS GDG files so that duplicate GDG generations are not created. GDGALLOC=GENERATION logic supports sites that use both SMS and non-SMS GDG data sets. The GDGENQ parameter is ignored and IBM Connect:Direct handles the ENQ logic. IBM Connect:Direct performs an exclusive SYSTEMS ENQ on QNAME NDMGDG and uses the base GDG name as the RNAME.

This exclusive ENQ causes a serialization within any IBM Connect:Direct on the system. First, IBM Connect:Direct issues a LOCATE to find the current absolute generation number. Next, IBM Connect:Direct performs an exclusive SYSTEM ENQ on QNAME SYSDSN and uses the data set name returned from LOCATE as the RNAME. If successful, IBM Connect:Direct then performs a shared SYSTEM ENQ on QNAME SYSDSN and uses the base GDG name as the RNAME. Dynamic allocation (SVC 99) is performed.

If the data set name allocated is not the same as what the LOCATE returned, the process ends with an SDEGDGRI error and the file is deleted. The two SYSDSN ENQs are not released until the end of the COPY step. The NDMGDG ENQ on the base is released (DEQueued) after the allocation is performed.

GENERATION is the default value.

DSNAME IBM Connect:Direct allocates by data set name (i.e., DATA.SET.NAME.G0000V00). If GDGENQ=YES parameter is coded, IBM Connect:Direct handles the ENQ logic. IBM Connect:Direct performs an exclusive SYSTEMS ENQ on QNAME NDMGDG and uses the base GDG name as the RNAME.

This exclusive ENQ causes a serialization within any IBM Connect:Direct on the system. First, IBM Connect:Direct issues a LOCATE to find the current absolute generation number. Next, IBM Connect:Direct performs an exclusive SYSTEM ENQ on QNAME SYSDSN and uses the data set name returned from LOCATE as the RNAME. If successful, IBM Connect:Direct then performs dynamic allocation (SVC 99) on the data set name that LOCATE returned.

If the ENQ is not successful, the process ends with an SDEGDGRI error and allocation does not occur. The SYSDSN ENQ is not released until the end of the COPY step. The NDMGDG ENQ on the base is released (DEQueued) after the allocation is performed.

If you code GDGALLOC = GENERATION, then for new non-SMS managed files, you must use one of the IBM-approved methods of supplying DCB attributes. For example, you could use one of these methods:

  • Code a model DSCB in the Process DCB=(model DSCB data set name).
  • Use an existing data set with the attributes desired for the new GDS data set DCB=(cataloged data set name) in the Process.
  • Have a model DSCB defined for the generation data group (GDG).
  • Use the LIKE=(cataloged data set name) parameter in the Process.

If you fail to use an approved method when creating new GDG data sets by generation, you will receive an allocation error of 048C.

Modifiable through MODIFY INITPARMS command: YES