### 9.3 Environment Variables ¶

Several environment variables affect GCL:

Environment Variable: GCL_MEM_MULTIPLE ¶

  A positive float indicating the fraction of available memory GCL should use. Defaults to 1.0.

Environment Variable: GCL_MEM_BOUND ¶

  A positive integer bounding GCL’s heap to 1<<(n+1) bytes. Trumps GCL_MEM_MULTIPLE. Defaults to sizeof(long)-1.

Environment Variable: GCL_GC_ALLOC_MIN ¶

  A positive float indicating the minimum fraction of heap to be allocated between garbage collection (GC) cycles. Defaults to 0.05.

Environment Variable: GCL_GC_PAGE_MIN ¶

  A positive float indicating the minimum fraction of heap to be allocated before garbage collection (GC) commences. Defaults to 0.5.

Environment Variable: GCL_GC_PAGE_MAX ¶

  A positive float indicating the maximum fraction of heap to be allocated after which garbage collection (GC) is mandatory. Defaults to 0.75.

Environment Variable: GCL_MULTIPROCESS_MEMORY_POOL ¶

  A string when set indicating a directory in which to place the file gcl_pool used for coordinating memory management among multiple GCL processes. This should be a local directory for performance reasons. Default is unset.

Environment Variable: GCL_WAIT_ON_ABORT ¶

  A non-negative integer indicating how many seconds to sleep before aborting on fatal error. Defaults to 0.