Check code that references the JES3 Locate Response control block in IATYLRS
Description
Starting with z/OS V2R2, the JES3 macro IATYLRS fixed entry is extended to support new generation data group (GDG) limits greater than 255. This change allows up to 999 active GDSs. The new format is called GDG Extended (GDGE). To support 999 active GDSs, the size of a JES3 Locator Response (LRS) fixed entry is extended and a new 2-byte GDG limit field is added.
LRSFIXEX EQU X'04' LRS extended fixed entry is used
LRSXFXLN DS H Length of LRS fixed entry
LRSGDLME DS H GDG limit from catalog management (GDGLIMTE)
When flag LRSFIXEX is set, the extended format of the LRS fixed entry is present and the value of field LRSXFXLN should be used for the length of the LRS fixed entry. Otherwise, the previous format of the LRS fixed entry is present and the existing equate LRSFXLEN is used for the length.
When existing flag LRSGDG is set, the LRS entry is for a GDG ALL request with a GDG limit value provided. When LRSFIXEX is set, the value of field LRSGDLME will contain the 2-byte GDG limit. Existing field LRSGDLIM is maintained and is set to the lesser of 255 and the value in LRSGDLME. When LRSFIXEX is not set, the value of field LRSGDLIM will contain the 1-byte GDG limit.
Table 1 provides more details about this migration action. Use this information to plan your changes to the system.
| Element or feature: | JES3 |
|---|---|
| When change was introduced: | z/OS V2R2. |
| Applies to migration from: | z/OS V2R1 and z/OS V1R13. |
| Timing: | After the first IPL of z/OS V2R2. |
| Is the migration action required? | Yes, if you have code that references the JES3 Locate Response control block as defined in IATYLRS. No changes are required if only the LRS fixed entry fields are referenced and if the existing GDG limit field LRSGDLIM is not referenced. |
| Target system hardware requirements: | None. |
| Target system software requirements: | None. |
| Other system (coexistence or fallback) requirements: | None. |
| Restrictions: | None. |
| System impacts: | None. |
| Related IBM® Health Checker for z/OS® check: | None. |
Steps to take
- Look for code, especially JES3 user exits, that refers to IATYLRS with the supplied address, referencing any of the following fields or equates from IATYLRS: LRSFXLEN, LRSGDLIM, or LRSDATA.
- Code using the length in equate LRSFXLEN to advance beyond the LRS fixed entry must be changed to use the value in field LRSXFXLN when flag LRSFIXEX is set.
- Code directly referencing the LRS data entry using the label LRSDATA must be changed to advance beyond the LRS fixed entry using the length value in field LRSXFXLN or equate LRSFXLEN based upon the flag LRSFIXEX.
- Code using the GDG limit in LRSGDLIM must be changed to use the new 2-byte GDG limit in field LRSGDLME when flag LRSFIXEX is set.
Reference information
For more information about the GDGE format, see the descriptions of the GDGLIMIT and GDGLIMTE fields in z/OS DFSMS Managing Catalogs.