# z/OS Software Maintenance Checklist

Published with SARATH.KB. Adapt every item to the vendor documentation and the target site's change, security and recovery procedures.

## A. Baseline and reason

- [ ] Record current product release, FMIDs, service/SOURCEID baseline and runtime library level
- [ ] Classify maintenance: corrective APAR/PTF, HIPER/security, PE correction, preventive RSU, prerequisite for upgrade or vendor recommendation
- [ ] Capture symptom/exposure/business reason and affected systems
- [ ] Confirm whether USERMODs/local modifications touch affected elements

## B. Service intelligence

- [ ] Obtain service from authoritative IBM/vendor source
- [ ] Receive current enhanced HOLDDATA before selecting service
- [ ] Check whether intended PTFs are PE, superseded or have resolving PTFs
- [ ] Review ERROR, SYSTEM and USER HOLDs
- [ ] Review prerequisites/co-requisites and GROUPEXTEND closure
- [ ] Review relevant FIXCAT and target-system/coexistence/product-install categories
- [ ] For preventive service, define RSU/SOURCEID policy and candidate scope
- [ ] Identify required operator/migration/configuration actions in HOLD SYSTEM data

## C. Change design

- [ ] Identify runtime activation method: dynamic, refresh, library sync, STC recycle, subsystem restart or IPL
- [ ] Identify APF/LINKLIST/LPA/LLA and copied runtime-library impacts
- [ ] Identify data/configuration changes that must be backed out separately from SMP/E
- [ ] Define stabilization period and ACCEPT policy
- [ ] Define precise fallback including SMP/E RESTORE applicability and product-specific recovery

## D. SMP/E execution

- [ ] RECEIVE intended service and verify RECEIVE output
- [ ] Run APPLY CHECK with production selection/options
- [ ] Review all HOLD/requisite/MODID/link-edit output, not just RC
- [ ] Document and authorize any BYPASS
- [ ] APPLY approved service
- [ ] Verify target zone and expected elements/libraries changed
- [ ] Synchronize runtime copies if product executes outside target libraries

## E. Activation and validation

- [ ] Perform documented activation/recycle/refresh/IPL
- [ ] Verify executing module/product/service level
- [ ] Re-test original APAR symptom when corrective
- [ ] Run representative regression/integration tests
- [ ] Review startup/runtime logs, WTORs, health checks and monitoring
- [ ] Compare CPU/storage/I/O/log volume with baseline where material

## F. Close

- [ ] Retain APPLY CHECK/APPLY/HOLDDATA evidence
- [ ] Record installed PTFs/FIXCAT/RSU level in inventory
- [ ] Keep rollback ability during stabilization
- [ ] ACCEPT only according to site policy after validation
- [ ] Document lessons/known exceptions and next preventive-service action