gtpi1m61System Installation Support Reference

Synchronization of Globals

Global synchronization is a process by which global fields and records are dynamically maintained among 2 or more active I-streams in a loosely coupled (LC) or tightly coupled (TC) system. Synchronization involves offline data record generation, online restart processing, and real-time application interface (SYNCC macro) processing.

The offline portion of global synchronization involves creation of the system interprocessor global table (SIGT). An SIGT is generated for each subsystem in each CPC. The GLSYNC macro is used to create the offline SIGT. SIGT also requires that space be reserved on DASD for the #SGFRI record type. For each subsystem user, one #SGFRI record is required for each global field that is to be synchronized. When no global fields require synchronization, at least 2 #SGFRI-type records are still needed, because 2 system globals are automatically synchronized by SIP. The #SGFRI record type is defined by coding the SIP RAMFIL macro. (See "Coding the SIP Macros" in TPF System Generation for more information on the GLSYNC and RAMFIL macros.)

During system restart, online initialization (completion of the process started offline) is performed. Segments CNPR, CNPS, and CNPT complete initialization of sections 0 and 1 of the SIGT. The main storage and file address of each synchronizable global field or record is calculated and moved into the SIGT. A minimum of at least one field, a dummy field, is defined as synchronizable.

Application programs initiate the online synchronization process when the SYNCC macro is issued. Copy member CSYN of the CSECT CCNUCL (Global Synchronization Service Routines) determines the type of SYNCC macro request and performs the requested function. Segment CNPU is activated to synchronize a field or record among all of the active I-streams in all active CPCs.

Requirements for Synchronization

The following requirements must be satisfied before global fields or records can be synchronized between tightly coupled or loosely coupled processors:

Maximum Values for Synchronized Fields and Records

The maximum field and record sizes are:

The maximum number of fields or records are: