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ABCs of z/OS System Programming Volume 3 - IBM Redbooks

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7.4 CICS function shipping before VSAM RLS<br />

CICS<br />

AOR<br />

CICS<br />

AOR<br />

CICS<br />

AOR<br />

CICS<br />

AOR<br />

<strong>System</strong> 1<br />

AOR = Application Owning Region<br />

FOR = File Owning Region<br />

Figure 7-4 CICS function shipping before VSAM RLS<br />

<strong>System</strong> n<br />

CICS function shipping<br />

Prior to VSAM RLS, a customer information control system (CICS) VSAM data set was<br />

owned and directly accessed by one single CICS. Shared access across CICS Application<br />

Owning Regions (AORs) to a single VSAM data set was provided by CICS function shipping.<br />

With function shipping, one CICS File Owning Region (FOR) accesses the VSAM data sets<br />

on behalf <strong>of</strong> other CICS regions (see Figure 7-4).<br />

Problems<br />

There are a couple <strong>of</strong> problems with this kind <strong>of</strong> CICS configuration:<br />

► CICS FOR is a single point <strong>of</strong> failure.<br />

► Multiple system performance is not acceptable.<br />

► Lack <strong>of</strong> scalability.<br />

Over time the FORs became a bottleneck because CICS environments became increasingly<br />

complex. CICS required a solution to have direct shared access to VSAM data sets from<br />

multiple CICSs.<br />

CICS<br />

FOR<br />

VSAM<br />

CICS<br />

AOR<br />

CICS<br />

AOR<br />

CICS<br />

AOR<br />

CICS<br />

AOR<br />

Chapter 7. DFSMS Transactional VSAM Services 383

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