z/OS V1R6.0 DFSMS Access Method Services for Catalogs

ALTERget exclusive control of the data set’s volume, a task in one system issuesthe RESERVE macro. The level of cross-system sharing allowed by VSAMapplies only in a multiple operating system environment.The cross-system sharing options are ignored by VSAM RLS or DFSMStvsprocessing. The values are:1 Reserved.2 Reserved.3 Specifies that the data set can be fully shared. With this option,each user is responsible for maintaining both read and writeintegrity for the data the program accesses. User programs thatignore write integrity guidelines can cause VSAM program checks,uncorrectable data set problems, and other unpredictable results.The RESERVE and DEQ macros are required with this option tomaintain data set integrity. (For information on using RESERVEand DEQ, see z/OS MVS Programming: Authorized Assembler ServicesReference LLA-SDU and z/OS MVS Programming: AuthorizedAssembler Services Reference ALE-DYN.)4 Specifies that the data set can be fully shared. For each request,VSAM refreshes the buffers used for direct processing. This optionrequires that you use the RESERVE and DEQ macros to maintaindata integrity while sharing the data set. Improper use of theRESERVE macro can cause problems similar to those describedunder SHAREOPTIONS 3. (For information on using RESERVEand DEQ, see z/OS MVS Programming: Authorized Assembler ServicesReference LLA-SDU and z/OS MVS Programming: AuthorizedAssembler Services Reference ALE-DYN.) .)Output processing is limited to update or add processing that doesnot change either the high-used relative byte address (RBA) or theRBA of the high key data control interval if DISP=SHR is specified.Abbreviation: SHRSTORAGECLASS(class)For SMS-managed data sets: Gives the name, 1 to 8 characters, of the storageclass. Your storage administrator defines the names of the storage classes youcan assign. A storage class is assigned when you specify STORAGECLASS oran installation-written automatic class section (ACS) routine selects a storageclass when the data set is created. Use the storage class to provide the storageservice level to be used by SMS for storage of the data set. The storage classprovides the storage attributes that are specified on the UNIT and VOLUMEoperand for non-SMS-managed data sets.When the storage or management class is altered for a DFSMShsm migrateddata set, ALTER will not recall the data set to make the change, provided noother parameters are specified.You must have RACF access authority to alter the storage class.If STORAGECLASS is used for a non-SMS-managed data set or if SMS isinactive, the ALTER command is unsuccessful.Abbreviation: STORCLASSTRNO(number)Specifies the number of concurrent catalog positioning requests that VSAM70 z/OS V1R6.0 DFSMS Access Method Services for Catalogs