Description: Starting in z/OS V1R12, most of the READONLY nucleus is backed by 1 MB pages. This makes protecting or unprotecting the READONLY nucleus with the PGSER macro difficult because the macro can only handle virtual storage pages backed by 4 KB pages. Therefore, the PGSER macro is changed, with APAR OA33782, to no longer support requests to protect and unprotect the READONLY nucleus if it is backed by 1 MB pages.
| Element or feature: | BCP. |
| When change was introduced: | z/OS V1R13. z/OS V1R12 by APAR OA33782. |
| Applies to migration from: | z/OS V1R12 without APAR OA33782. |
| Timing: | Before installing V2R1. |
| Is the migration action required? | Yes, if you use the PGSER macro to protect or unprotect the READONLY nucleus. |
| Target system hardware requirements: | None. |
| Target system software requirements: | None. |
| Other system (coexistence or fallback) requirements: | None. |
| Restrictions: | None. |
| System impacts: | Failure to discontinue use of PGSER to protect and unprotect READONLY nucleus that is backed by 1 MB pages will result in the ABEND18A reason codes indicated in "Steps to take". |
| Related IBM Health Checker for z/OS check: | None. |
Steps to take: Do not use PGSER to protect or unprotect the READONLY nucleus when it is backed by 1 MB pages. Users requiring the modification of READONLY nucleus should use the DATOFF macro.
Reference information: For detailed information about PGSER, see For detailed information about PGSER, see z/OS MVS Programming: Authorized Assembler Services Reference LLA-SDU.