RESALL

What “Resource Allocation” Means

A sort or merge step needs resources: memory for sort work and temporary datasets (SORTWK) for data that does not fit in memory. DFSORT can request or reserve these at different times and in different ways. RESALL is an option that affects this resource allocation behavior—for example whether DFSORT reserves a certain amount up front, or how it requests work space. The goal is often to avoid failures (e.g. ICE046A, ICE083A) when resources are tight or to make allocation more predictable. Because the precise meaning and syntax of RESALL can vary by product release and installation, the following is a general overview; you should confirm details in your DFSORT documentation.

Typical Placement and Syntax

RESALL is usually specified in the OPTION statement in SYSIN. Some versions may support it on the EXEC PARM or via DFSPARM. The keyword may stand alone (OPTION RESALL) or take operands (e.g. RESALL=value). Check your DFSORT Application Programming Guide for the exact form and any allowed values.

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  OPTION RESALL,DYNALLOC,FILSZ=E5000000
  SORT FIELDS=(1,80,CH,A)

Combining RESALL with DYNALLOC and FILSZ is common when tuning for large or variable workloads; the interaction is product-dependent.

How RESALL Relates to Other Options

RESALL does not replace DYNALLOC, SIZE, or FILSZ; it can influence the overall allocation strategy. For example, with RESALL, DFSORT might reserve resources earlier or request a minimum amount, depending on your version. Use your product documentation to see the exact effect and recommended combinations.

When to Use RESALL

• Site or tuning guidelines — Your installation may recommend RESALL for certain job types or sizes.
• Avoiding late allocation failures — In some configurations, reserving resources up front can reduce the chance of failures when the system is under load.
• Predictable resource use — When your site wants more predictable allocation behavior, RESALL may be part of the recommended option set.

If your documentation does not mention RESALL, or your job runs fine without it, you may not need to specify it. When in doubt, consult your systems programmer or DFSORT installation guide.

Finding Exact Behavior for Your Version

Because RESALL is not always described in brief tutorials and its behavior can differ by release:

• Use the z/OS DFSORT Application Programming Guide (or equivalent for your product and z/OS level) and search for “RESALL” or “resource allocation.”
• Check your installation’s DFSORT customization or PARM documentation for any overrides or recommended options.
• If you use IBM z/OS Beyond Sort or a different sort product, refer to that product’s documentation; option names and behavior may differ.

Explain It Like I'm Five

When you need tables to sort cards, you can either grab them when you need them or say “I need tables now” at the start. RESALL is like telling the teacher “reserve my tables at the beginning” so they are set aside for you. The exact rules (how many tables, when) depend on your school’s (installation’s) rules, so we check the rule book (documentation) to see exactly what RESALL does.

Exercises

1. Look up “RESALL” or “resource allocation” in your site’s DFSORT Application Programming Guide. What syntax and operands are documented for your version?
2. Your job gets ICE083A under heavy load. Besides RESALL, what other options (e.g. FILSZ, DYNALLOC, SIZE) would you review and why?
3. Does your installation’s DFSORT tuning guide recommend RESALL for large sorts? If so, what value or form do they suggest?
4. If RESALL is not in your product’s index, which other document (e.g. Installation and Customization, PARM reference) might describe it?