Technical requirements

Alternate Access requires no changes to the operating system, hardware, or any BMC online components; however, Alternate Access must execute from an APF-authorized library.

The priority of TASs should be set above priorities for batch jobs and should be set similar to the priorities for BMC online components that you are running.

Hardware considerations

Alternate Access has the following hardware considerations:

• DASD
  The approximate number of 3390-cylinders that are required for the Alternate Access target libraries is 32; for the Alternate Access distribution libraries, the approximate number is 38.
  

• Virtual storage
  BMC recommends that you allow 4096 K of private storage to run Alternate Access. The default LAS and TAS procedures specify REGION=4096 on the EXEC statement. BMC recommends that you do not change this value.
  
  The following table lists the CSA requirements for Alternate Access:

  Address Space Type	CSA
  LAS	128 Bytes
  Each VTAM TAS	284 Bytes
  All EXCP TASs The first EXCP TAS to initialize after an IPL allocates 6 K of CSA; this allocation supports any number of EXCP sessions and remains allocated until the next IPL.	6 K

Software considerations

Alternate Access requires an OS/390 or z/OS configuration and operates with the following ESM system software products:

• RACF 1.8.0 or later
• CA-TOP SECRET 4.2 or later
• CA-ACF2 5.2 or later