SD37 secondary allocation unavailable

SD37 means no secondary space was available when the dataset tried to extend — closely related to SB37, but specifically about secondary allocation.

What it means

• The primary allocation filled up and the system could not obtain secondary extents.
• Either none were coded or the volume has no room left.

Common causes

• SPACE coded with primary only, e.g. SPACE=(CYL,50) with no secondary.
• Volume full so secondary extents cannot be allocated.
• Unexpected output volume from a program bug.

How to diagnose

• Inspect the SPACE parameter: confirm a secondary quantity is coded.
• Check volume free space with the storage team.
• Verify record counts written before failure.

How to fix it

• Code secondary space: SPACE=(CYL,(50,20)).
• Free volume space or add volumes to the storage group.

Example: Always code secondary space

The ",20" secondary allocation is what prevents SD37.

Interview tip

• Q: How would you troubleshoot a SD37 secondary allocation unavailable in production?
• A: I would verify secondary space is coded and check volume free space, then correct whichever is missing.

Prevention checklist

• Standard: always code primary and secondary.
• Alert on volumes above 85% full.